Improve o2checkcode

[vkucera]

• Allow auto-detect of .clang-tidy. (Report if found.)
• Remove explicit list of Clang-Tidy checks.
  • Configuration is taken from .clang-tidy if found. (Requires Update Clang-Tidy config file AliceO2Group/AliceO2#15321)
  • Additional check configuration from O2_CHECKER_CHECKS is appended via the -checks command line option. (Report the provided value.)
• Print enabled checks before running instead of all available.
• Don't turn warnings into errors. Report both.
• Fix unbound ALIBUILD_BASE_HASH.

FIXME: git diff can fail silently, leading to an early exit due to an empty list of changed files. This is currently happening in the alidist fullCI check.

[sawenzel]

where is the default list of O2_CHECKER_CHECKS now maintained? I think such default list would be useful.

[vkucera]

See the description.

[sawenzel]

My question is maybe more, why is it a good thing to delete the default list of checks from the recipe?
Initially the recipe was meant to be fully configured for ALICE and just typing aliBuild build o2checkcode should be enough. Now, it seems, you need to inject more information from the outside.

[vkucera]

Typing aliBuild build o2checkcode is still enough, plus the configuration is stored at a standard place which makes it reusable and modifiable independently of o2checkcode, alidist and aliBuild.