use perl instead of sed in style checks for portability to MacOS (AMR…

…eX-Codes#4127)

## Summary

`sed -i` does not function the same for GNU and BSD sed and a simple
portable command between the two is apparently not possible. Therefore,
the style check scripts do not work by default when running on Macs,
unless the user installs `gsed` and aliases `sed` to run that instead.
For portability,`perl` can be used instead of `sed`.

## Additional background

Proposed solution taken from here:
https://stackoverflow.com/questions/4247068/sed-command-with-i-option-failing-on-mac-but-works-on-linux

.github/workflows/style/check_tabs.sh

@@ -20,7 +20,7 @@ find . -type d \( -name .git \
                     -a ! -name "*.lex.h" -a ! -name "*.lex.nolint.H" \) \
                \) \
     -exec grep -Iq . {} \; \
-    -exec sed -i 's/\t/\ \ \ \ /g' {} +
+    -exec perl -i -pe's/\t/\ \ \ \ /g' {} +
 
 gitdiff=`git diff`
 

.github/workflows/style/check_trailing_whitespaces.sh

@@ -20,7 +20,7 @@ find . -type d \( -name .git \
                     -a ! -name "*.lex.h" -a ! -name "*.lex.nolint.H" \) \
                \) \
     -exec grep -Iq . {} \; \
-    -exec sed -i 's/[[:blank:]]\+$//g' {} +
+    -exec perl -i -pe's/[[:blank:]]+$//g' {} +
 
 gitdiff=`git diff`