frameworks: Add highly concurrent MessageQueue implementations

Move MessageQueue.java to LegacyMessageQueue.java and add two variants
on an optional implemenation which we can switch on via build flag.
The 'legacy' MessageQueue class stays the default. ConcurrentMessageQueue
and SemiConcurrentMessageQueue keeps the same API from MessageQueue.

We enqueue new messages onto a lockless (treiber) stack. Next()
walks the stack and enqueues items into a priority queue which is
then used to determine the next messages to deliver.
This gives us amortized constant time insertions - next() pays
the price of O(Log n) inserts.

Remove is still a liner time operation as the API around it makes it
impossible to remove items without doing a full scan.

For ConcurrentMessageQueue, remove() runs in parallel to insert and next().

For SemiConcurrentMessageQueue, remove() and next() are mutually excluded.

The difference between ConcurrentMessageQueue and SemiConcurrentMessageQueue
is in priority queue implementations. One uses the lockless
ConcurrentSkipListSet while the other uses PriorityQueue with a lock around
priority queue operations.

We are not sure about the average case performance of ConcurrentSkipListSet,
hence the 'SemiConcurrent' implementation.

Flag: build.RELEASE_PACKAGE_MESSAGEQUEUE_IMPLEMENTATION
Test: atest MessageQueueTest
Test: boot phone and use it
Bug: 336880969
Change-Id: I69108655dfcde6e54c5bb5d00f3b3b47967d814f