InputTracer: Use InputThread instead of std::thread

We need to query PackageManager from the trace instace, so we will need
access to the JVM from the tracer thread. Since std::thread does not
have access to the JVM, use InputThread instead.

Bug: 210460522
Test: manual with perfetto
Change-Id: Ifb618765a269ae928d2310fc6af3daf55bf10dc9