ActivityManager: Throw correct exception during Uid Frozen registration

registerUidFrozenStateChangedCallback is throwing
IllegalArgumentException, but the javadoc says it throws
IllegalStateException. We want to follow the doc in this case so fix the
function to throw IllegalStateException.

While we're here we can add some missing permission and Null checks.

We were also missing a description for onUidFrozenStateChanged, add one.

Bug: 274010383
Test: Compiled
Change-Id: Ie798ba87f043a8a45a8d3233d275ccab9f97d14f