Fold perfetto_src_tracing_ipc into libperfetto_client

Until now tracing:ipc was a static library and was depended on by
a bunch of android.bp targets (mainly CTS tests and, recently, surfaceflinger).
The newly introduced libperfetto_client_experimental should have linked in
also the tracing:ipc target, but accidentally it didn't.
This CL is fixing this, by making tracing:ipc a source set and by making the
CTS targets depend on the superset libperfetto_client.

Sadly, however, surfaceflinger ended up depending on both libperfetto_client
and tracing_ipc. We can't easily remove tracing_ipc because doing so would
require multi-repo atomic changes. Instead this CL leaves an empty
tracing_ipc target, to keep surfaceflinger building. The target will be removed
as soon as surfaceflinger drops the dependency and depends only on
libperfetto_client.

Bug: 140591279
Change-Id: If558bcd18b0987ec3043b7d05e6761aed3e2ecda