Make a copy of data stored in LockSettingsStorage cache

In general the cache should store copies of the original data
to prevent the caller from accidentally corrupting the cache after
the data is cached. This wasn't an issue until recently when
LockSettingsService starts to aggressively zeroize buffers,
which caused some unit test failures.

Bug: 120484642
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/locksettings/
Change-Id: I8cc61789f19613cca8ed36ca34aa42fe6b2ad674