pw_ide: Process multiple comp DBs

Some tools and build systems can output multiple compilation databases
instead of just one. Now you can provide either a path to a single file
or a glob to multiple files to process. The result will still be a set
of consistent target-specific compilation databases.

Change-Id: I6fb6e412292ee0a4ec1a5fcbd61c5da3c6e7876f
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/113312
Reviewed-by: Anthony DiGirolamo <tonymd@google.com>
Commit-Queue: Chad Norvell <chadnorvell@google.com>