Reduce PR lint time by checking changed files

[chestercheng]

Currently, the lint workflow in PR takes a long time.
This is because it runs lint checks on the entire codebase, even when only a few files are changed.

To improve CI reduce waiting time, It should be possible to run lint only on files that are modified in the PR.
This could speed up PR checks and improve developer productivity.

[yungyuc]

We will need to improve cmakelists to allow it to clang-tidy (actually build) only selected files, and find a way to single out the C++ files and their dependency (headers included) in each PR/commit.

[yungyuc]

Assigned to @ExplorerRay . Please briefly describe how you would like to start with the work.

[ExplorerRay]

After reading current CMakeLists.txt, I guess the current lint process is triggered by make pilot with USE_CLANG_TIDY=ON because I am not that familiar with CMake currently. Because compiling pilot also need modmesh source code to be built, those codes are also built with USE_CLANG_TIDY=ON.
I think I need to do some experiments locally first to check my guess is right. Then, survey how to split compiling different components so that every component can be compiled with USE_CLANG_TIDY=ON separately.

[yungyuc]

Sounds like a plan.

[yungyuc]

After reading current CMakeLists.txt, I guess the current lint process is triggered by make pilot with USE_CLANG_TIDY=ON because I am not that familiar with CMake currently. Because compiling pilot also need modmesh source code to be built, those codes are also built with USE_CLANG_TIDY=ON. I think I need to do some experiments locally first to check my guess is right. Then, survey how to split compiling different components so that every component can be compiled with USE_CLANG_TIDY=ON separately.

@ExplorerRay I created the sub-issue #679 based on your comment and assigned it to you.