Add tools property and entrypoint for workflows

[bastonero]

Fixes #6865

[codecov]

Codecov Report

Attention: Patch coverage is 23.07692% with 20 lines in your changes missing coverage. Please review.

Project coverage is 78.56%. Comparing base (5168032) to head (b3a9928).

Files with missing lines	Patch %	Lines
src/aiida/orm/nodes/process/workflow/workchain.py	30.00%	14 Missing ⚠️
src/aiida/tools/workflows/base.py	0.00%	4 Missing ⚠️
src/aiida/tools/workflows/__init__.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6884      +/-   ##
==========================================
- Coverage   78.59%   78.56%   -0.03%     
==========================================
  Files         567      569       +2     
  Lines       43092    43117      +25     
==========================================
+ Hits        33865    33871       +6     
- Misses       9227     9246      +19     

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