Collect info on non-cc sources in a cc module.

Cc modules in Soong can contain non-cc srcs, collect information on
whether they exist in a module. This is not entirely precise as globs
are not evaluated and srcs from other modules (e.g. filegroups,
generated sources) are not handled; however, it should give a decent
lower bound on how often each type occurs.

Bug: 194938896
Test: SOONG_DUMP_JSON_MODULE_GRAPH=/tmp/json_srcs m nothing and verify
      outputs
Change-Id: I7ad52e863727cf5fa4e8d41cf04d27c86e395c6d