[clang-tidy][docs] Implement alphabetical validation of clang-tidy docs.

[vbvictor]

This is sub-issue to implement rule "keep some files in alphabetical format", see #165999.

These files are:
https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/docs/clang-tidy/checks/list.rst?plain=1
https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/docs/ReleaseNotes.rst?plain=1

It should be a simple python script that we could run as a lit test, like this:
#118154

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: Baranov Victor (vbvictor)

This is sub-issue to implement rule "keep some files in alphabetical format", see https://github.com//issues/165999.

These files are:
https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/docs/clang-tidy/checks/list.rst?plain=1
https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/docs/ReleaseNotes.rst?plain=1

It should be a simple python script that we could run as a lit test, like this:
#118154

[EugeneZelenko]

We also need to add check for duplicated entries in Changes in existing checks section. Some developers made such mistakes and it even harder to spot when new entry is added in non-alphabetical order.

[zeyi2]

I implement a simple check that looks like this:

Command Output (stdout):
--
# RUN: at line 1
/usr/bin/python3.13 /home/mitchell/Documents/projects/llvm-project/clang-tools-extra/test/clang-tidy/../../docs/tools/dump_clang_tidy_sorted_checks_list.py -o /home/mitchell/Documents/projects/llvm-project/build/tools/clang/tools/extra/test/clang-tidy/Output/docs_sorted.test.tmp.list
# executed command: /usr/bin/python3.13 /home/mitchell/Documents/projects/llvm-project/clang-tools-extra/test/clang-tidy/../../docs/tools/dump_clang_tidy_sorted_checks_list.py -o /home/mitchell/Documents/projects/llvm-project/build/tools/clang/tools/extra/test/clang-tidy/Output/docs_sorted.test.tmp.list
# RUN: at line 2
diff --strip-trailing-cr /home/mitchell/Documents/projects/llvm-project/build/tools/clang/tools/extra/test/clang-tidy/Output/docs_sorted.test.tmp.list    /home/mitchell/Documents/projects/llvm-project/clang-tools-extra/test/clang-tidy/../../docs/clang-tidy/checks/list.rst
# executed command: diff --strip-trailing-cr /home/mitchell/Documents/projects/llvm-project/build/tools/clang/tools/extra/test/clang-tidy/Output/docs_sorted.test.tmp.list /home/mitchell/Documents/projects/llvm-project/clang-tools-extra/test/clang-tidy/../../docs/clang-tidy/checks/list.rst
# RUN: at line 5
/usr/bin/python3.13 /home/mitchell/Documents/projects/llvm-project/clang-tools-extra/test/clang-tidy/../../docs/tools/dump_clang_tidy_sorted_release_notes.py -o /home/mitchell/Documents/projects/llvm-project/build/tools/clang/tools/extra/test/clang-tidy/Output/docs_sorted.test.tmp.rn
# executed command: /usr/bin/python3.13 /home/mitchell/Documents/projects/llvm-project/clang-tools-extra/test/clang-tidy/../../docs/tools/dump_clang_tidy_sorted_release_notes.py -o /home/mitchell/Documents/projects/llvm-project/build/tools/clang/tools/extra/test/clang-tidy/Output/docs_sorted.test.tmp.rn
# RUN: at line 6
diff --strip-trailing-cr /home/mitchell/Documents/projects/llvm-project/build/tools/clang/tools/extra/test/clang-tidy/Output/docs_sorted.test.tmp.rn /home/mitchell/Documents/projects/llvm-project/clang-tools-extra/test/clang-tidy/../../docs/ReleaseNotes.rst
# executed command: diff --strip-trailing-cr /home/mitchell/Documents/projects/llvm-project/build/tools/clang/tools/extra/test/clang-tidy/Output/docs_sorted.test.tmp.rn /home/mitchell/Documents/projects/llvm-project/clang-tools-extra/test/clang-tidy/../../docs/ReleaseNotes.rst
# .---command stdout------------
# | *** /home/mitchell/Documents/projects/llvm-project/build/tools/clang/tools/extra/test/clang-tidy/Output/docs_sorted.test.tmp.rn
# | --- /home/mitchell/Documents/projects/llvm-project/clang-tools-extra/test/clang-tidy/../../docs/ReleaseNotes.rst
# | ***************
# | *** 184,199 ****
# |   New checks
# |   ^^^^^^^^^^
# |   
# |   - New :doc:`bugprone-derived-method-shadowing-base-method
# |     <clang-tidy/checks/bugprone/derived-method-shadowing-base-method>` check.
# |   
# |     Finds derived class methods that shadow a (non-virtual) base class method.
# | - 
# | - - New :doc:`bugprone-invalid-enum-default-initialization
# | -   <clang-tidy/checks/bugprone/invalid-enum-default-initialization>` check.
# | - 
# | -   Detects default initialization (to 0) of variables with ``enum`` type where
# | -   the enum has no enumerator with value of 0.
# |   
# |   - New :doc:`cppcoreguidelines-pro-bounds-avoid-unchecked-container-access
# |     <clang-tidy/checks/cppcoreguidelines/pro-bounds-avoid-unchecked-container-access>`
# | --- 184,199 ----
# |   New checks
# |   ^^^^^^^^^^
# |   
# | + - New :doc:`bugprone-invalid-enum-default-initialization
# | +   <clang-tidy/checks/bugprone/invalid-enum-default-initialization>` check.
# | + 
# | +   Detects default initialization (to 0) of variables with ``enum`` type where
# | +   the enum has no enumerator with value of 0.
# | + 
# |   - New :doc:`bugprone-derived-method-shadowing-base-method
# |     <clang-tidy/checks/bugprone/derived-method-shadowing-base-method>` check.
# |   
# |     Finds derived class methods that shadow a (non-virtual) base class method.
# |   
# |   - New :doc:`cppcoreguidelines-pro-bounds-avoid-unchecked-container-access
# |     <clang-tidy/checks/cppcoreguidelines/pro-bounds-avoid-unchecked-container-access>`
# `-----------------------------
# error: command failed with exit status: 1

#166038

It currently only validates the alphabetical order, I will open a draft PR after some refactoring and improvements.

[vbvictor]

We also need to add check for duplicated entries in Changes in existing checks section. Some developers made such mistakes and it even harder to spot when new entry is added in non-alphabetical order.

I'm fine if in this issue we would only implement alphabetical structure.
I can make a separate sub-issue for duplicated entries. (Smaller steps are easier to achieve and more encouraging IMO)

CC @zeyi2