Hyperlinks and refined dwyu matching

Lots of little improvement. So many in fact, that I forgot all of them, but here are some highlights:

• Terminal UI feature: Provide hyperlinks in log messages and bant print
  (if your terminal can deal with them). Now it is possible to directly jump to the code referenced from logs and prints.
• CC preprocessor more advanced: now also takes #ifdef into account, provided
  from defines = [] in dependency rules. Also, <>-angle-bracket includes
  are considered (with flags controlling what to do with them).
• visibility: understand package groups to be able to more fine-grained determine which rules it is ok to depend on.
• Add tags to better steer dwyu: avoid_dep (to make a choice if there are multiple
  dependencies (often from legacy reasons) that provide the same headers), keep_dep (like # keep comment,
  but at the source, similar effect to alwayslink=True or library without headers).

On BCR:

bazel_dep(name = "bant", version = "0.3.0")