This will allow frame capture/replay to more easily emulate object
handle manipulation. It also provides a bit of type safety. Also
generalizes ResourceMap to handle non-GLuint IDs.

Bug: angleproject:3611
Change-Id: I174fd260f326e0dbe2aca3f818215c91d82cf48c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1706559
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>