Plug-and-play Bazel integration (local-only)

[varungandhi-src]

There are few different sub-parts here (which may make sense to split out into separate issues):

• Use aspects instead of a compilation database.
• Infer third-party repository information for cross-repo support.
• Provide an easy way to integrate into a Bazel build. Basically, "copy these few lines into your WORKSPACE file, and run this one command".

It may be worth splitting out each of these into separate issues.