Remove installFiles from ModuleBase.

This is to limit the direct accesses to the internal fields of a
module in order to better support incremental caching. To access
the install files data from singleton context or other modules'
context use providers thru the provided wrapper; to access it
from the same module inside GenerateBuildActions use ctx which is
short-lived only inside this method.

Bug: 358425833
Test: CI
Change-Id: I337b07a2ef95fb2a898ac2f9277160a3f76a603c