Print more detailed version information; allow custom version suffix

[illuhad]

• By default, the git commit hash is appended to the version as +gitHASH, with HASH being the git hash.
• Suffix can be overridden using -DACPP_VERSION_SUFFIX in cmake
• This also adds a new field to syclcc.json called version-suffix.
• Changes macros in code from HIPSYCL_VERSION_<TYPE> to ACPP_VERSION_<TYPE>. Whether macros should better use ADAPTIVECPP_ prefix still needs to be discussed; I've used ACPP_ for consistency with cmake.

The new version string is e.g. presented when invoking acpp --acpp-version, but might also be visible in the version number that the clang plugin presents itself, or the version_string() that our SYCL headers use.

Fixes #1165

[pszi1ard]

A few tips:

• it can be very useful to have a date in the version string of a build from git since git hashes do not help understanding whether a specific build is from a day a month or a year ago.
• as a developer, you may find it useful to know whether your build is from a dirty tree or not ;)

There are a few more cases you may want consider, as inspiration take a look at our versioning:
https://gitlab.com/gromacs/gromacs/-/blob/main/cmake/gmxVersionInfo.cmake?ref_type=heads#L167-193

and here is the code we use to generate the git-based version string: https://gitlab.com/gromacs/gromacs/-/blob/main/cmake/gmxGenerateVersionInfo.cmake

[illuhad]

Thanks for the suggestions @pszi1ard :-) I have expanded the version string to include head date, git branch and dirty flag. Example string is now:

$ install/bin/acpp --acpp-version
acpp [AdaptiveCpp compilation driver], Copyright (C) 2018-2023 Aksel Alpay and the AdaptiveCpp project
  AdaptiveCpp version: 23.10.0+git.f19037f9.20231013.branch.feature/detailed-version-information.dirty