This should speed up pre-commit a bit as only files that are staged will
be processed, and clang-format and shellcheck are only invoked once, not
for every file. When no arguments are given (e.g. on CI), it still uses
'git ls-files'.
Problem:
- The first lint check that fails results in all subsequent checks not
being run.
Solution:
- Run all the lint checks aggregating the number of failures.
- Return a non-0 exit code if any have failed.
Problem:
- It is possible for a new test file to be added to the `AK/Tests`
directory without being added to the corresponding
`CMakeLists.txt`. This results in the tests not being run.
Solution:
- As part of CI linting, verify that all the `AK/Tests/Test*.cpp`
files are mentioned in the `CMakeLists.txt`.
