Add Java 6's ResourceBundle/Properties API.

Add Java 6's ResourceBundle/Properties API.

I've pretty much taken the upstream ResourceBundle implementations
as-is, putting back our string-to-locale conversion, removing a bit
of duplication and non-free, non-spec EBCDIC support, and hard-coding
the text of the MissingResourceExceptions (since harmony's changed
its message catalog from ours, so I had to touch those bits of the
code anyway).

(Why haven't I bothered to pay much attention to the resource bundle
implementations? Because I already rewrote our only code that was
using them to not use them, and third-party developers should be
using Android's resource system instead. There's very little chance
anyone needs Java resource bundles. I paid some attention to Properties,
because they're still somewhat useful.)

Also remove various unused messages, and update our tests. I've mostly
_not_ taken the upstream tests, because it would require a lot of work
that we'll be doing anyway when we switch to using their test suite
properly.

I ran the jtreg tests we're able to run, and the normal-case ones (plus
the stress test) seemed okay.

Bug: 2497395
Change-Id: I91606df0dc1a45e6974fbb27a0d334af87254f0b