Fix debugger deadlock.

Fixes a deadlock between the event thread lock and the processing request
lock where the JDWP thread and the event thread wait for each other. We now
move the call to StartProcessingRequest after the call to SetWaitForEventThread
in JdwpState::ProcessRequest so locks are taken in the same order in both
threads.

Also adds some thread safety annotations and JDWP verbose logs for debug (only
enabled if we pass the -verbose:jdwp option to the runtime).

Bug: 13165103
Change-Id: I4e8b6526d973bfee56e69e8e14eddf56adfa1939