Makefile: add clang-format

[dkropachev]

It adds clang-format to the list of linters for c/cpp code.
Also it applies format changes suggested by clang-format

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• PR description sums up the changes and reasons why they should be introduced.
• I have enabled appropriate tests in .github/workflows/build.yml in gtest_filter.
• I have enabled appropriate tests in .github/workflows/cassandra.yml in gtest_filter.

[Lorak-mmk]

I wonder if this this something that should be done in this project. C/Cpp files are only test-related, copied verbatim from original cpp-driver and modified a bit. Maybe it's of more value to reduce amount of modifications to them, so that it is easier to diff them eith their original versions?

[Lorak-mmk]

Another issue: biggest cause for automated code formatting is consistency of formatting. This PR uses default style of clang-format, without any config. This is consistent neither with scylla / seastar style, nor with original cpp-driver style.
Imo if we were to add automated formatting it should mimic one of those style as close as possible. Personally I'd be for the style of original cpp-driver, becuse it will make it easier to read both codebases together (which is something I know I had to do many times when developing this project).

[muzarski]

There is a clang-format config file in cpp-driver's repo: https://github.com/datastax/cpp-driver/blob/master/.clang-format. We should definitely use it,

[dkropachev]

There is a clang-format config file in cpp-driver's repo: https://github.com/datastax/cpp-driver/blob/master/.clang-format. We should definitely use it,

Thanks, I have copied it.
@Lorak-mmk , does it address your concerns ?

[Lorak-mmk]

How did you generate the last commit? It looks like it doesn't respect the config. Example: look at src/aligned_storage.hpp. Comment was reflown in your PR, despite not being longer than 100 characters (which is the limit in config

I checked out the PR, dropped the last commit and executed make fix-clang-format - this seems to result in correct changes (I don't see wrongly reflown comments).

Another issue: I think that third_party folder should be skipped. Those are basically dependencies, not something that we should edit.

[dkropachev]

How did you generate the last commit? It looks like it doesn't respect the config. Example: look at src/aligned_storage.hpp. Comment was reflown in your PR, despite not being longer than 100 characters (which is the limit in config

I checked out the PR, dropped the last commit and executed make fix-clang-format - this seems to result in correct changes (I don't see wrongly reflown comments).

Another issue: I think that third_party folder should be skipped. Those are basically dependencies, not something that we should edit.

Thanks, both done, third_party excluded, last commit removed and formatting reapplied.

[muzarski]

Please squash first and second commits, otherwise LGTM

[dkropachev]

Please squash first and second commits, otherwise LGTM

@Lorak-mmk , are you ok with it ?