Move ResourceLoader classes to their own namespace. Strip the
"ResourceLoader" prefix from all except ResourceLoader itself.
Move the tests by analogy.
I used a namespace alias "RL" in some callers since RL\Module is less
ambiguous at the call site than just "Module".
I did not address DependencyStore which continues to have a non-standard
location and namespace.
Revert of a241d83e0a.
Bug: T308718
Change-Id: Id08a220e1d6085e2b33f3f6c9d0e3935a4204659
3e2653f83b