Add new soongdbg command and a big json file full of soong debugging info.

In order to use soongdbg, you must run analysis with GENERATE_SOONG_DEBUG=true set
in the environment.

Test: GENERATE_SOONG_DEBUG=true m nothing ; soongdbg ...
Change-Id: If43676fe2784f05cd87c0ecb4a46ab676b91023f