Move activity timeouts to ActivityRecord (81/n)

Reduces reliance on ActivityStack
Also:
- Removed AS#mWindowManager and use mWmService instead
- Renames AS#mService to mAtmService
- Removed AS#mLruActivities which was only used for logging

Change-Id: I61ade9104b9be65b69f68f3055ad2c226d364202
Test: Existing tests pass.
Bug: 80414790