Fix popular chinese app crashes in new API

Resources.registerResourcePaths() API implementation used to
always create a new asset manager object when updating an
object that could be in use already. This was to prevent a
case when we change the assets mid-high level oepration.

Turns out the other case is more prevalent: when an app
uses the object as a key holding some own resources
customization, and changing the object suddenly invalidates
that mapping, causing the apps to fail loading their own
resources

This change switches to the in-place update with the full
config recalculation under a lock. It's slow, but hopefully
doesn't cause too many discrepancies in the resource lookups

Bug: 412905284
Test: atest ResourcesManagerTest
Flag: EXEMPT bugfix
Change-Id: I30e162e504724b30cb0d892c950ad6c3057804d2