Adding language flag

[fosterbrereton]

• Added a --language flag (aliased to -x) that lets the user explicitly pass in the language Hyde's Clang driver should use for compilation. This is handy when the extension of the base file being processed by Hyde causes it to derive a different language than the author intends. For example, to compile a .h file as a C++ header, one would now invoke Hyde like so:

  hyde --language=c++ --auto-toolchain-includes /path/to/example.h --
  

• Bumped Clang to 18.1.8.
• Added Hyde version details to hyde --version:

  hyde --version
  hyde 2.0.2; llvm 18.1.8