[clang-tools-extra] Adding first version for which clang-tidy checks and their options are available (PR #162937)

[Baranov Victor via cfe-commits]

vbvictor wrote:

> Alright, sounds good to me! If we omit minor and patch versions, should I consider that LLVM v15 is referring to the latest v15 release (15.0.7) or the first one (15.0.0)? In case it ever matters and actually changes what checks/options are available. I feel like using the latest version (in this case, 15.0.7) would make the most sense.

Yes, let's go for the latest version (15.0.7).
We should also decide from what version we should start. AFAIK, `clangd` starts documenting from `clangd-11`. Do you have a version in your mind? I looked and `clang` [versioning](https://releases.llvm.org/) and probably 4 is the right place to start from because LLVM started to increase MAJOR version every release opposed to MINOR version increase for each new `3.x.x` release.

https://github.com/llvm/llvm-project/pull/162937