Improvement: indent ignore list and unification of indent scripts [1/2]

[holke]

Describe your changes here:

A slight overall of our indent scripts.

1. Add a list of ignored files to our indent script.
   Since clang-format only supports ignore files from version 18 and we use version 17, some bash magic was required to manually parse the list of ignored files.

We should consider updating to clang-format >= 18.

2. We had two scripts "t8indent" and "check_if_file_indented" that were nearly duplicates of each other.
   I cleaned this up by unifying the files such that "t8indent" is the only file with indentation code and has a new option "NO_CHANGE" and "check_if_file_indented" calls "t8indent" with that option.

Edit: I also fixed an unrelated typo in a comment in a t8_geometry file which kept the CI pipeline from failing. Usually i should have opened a new PR, but this was literally just one character and it was in a comment. So i thought i would get away with sneaking it into this PR to make the pipeline succeed.

Closes #1687
Preparation for #1675 and should be merged before #1522

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[holke]

I just noticed that t8indent.sh and check_if_file_indented.sh are nearly identical and i either have to replicate code and put it into check_if_file_indented.sh or unify those files.
Will do the later - but no time for it now.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.02%. Comparing base (e6b165a) to head (77d538e).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1688   +/-   ##
=======================================
  Coverage   74.02%   74.02%           
=======================================
  Files          98       98           
  Lines       18577    18577           
=======================================
  Hits        13751    13751           
  Misses       4826     4826           

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[holke]

Unified both scripts. However, there is still a bug since now all files are reported as indented by our pre-commit hook.

[lenaploetzke]

Nice changes! Just small comments

[lenaploetzke]

Suggested change

	# aways those filenames that we should ignore.
	# away those filenames that we should ignore.

[lenaploetzke]

A few more comments what is happening here for which options would be nice

[lenaploetzke]

Maybe also state here that you can use the option -o ?

[lenaploetzke]

Maybe add USAGE: ?