Use outerContext in the InputManager service

We're having some random crashes that are the
result of `InputManager` losing the reference
to the `Context` object. This will be resolved
as part of the refactoring being done in
b/267758905, but until that is completed, we
will change the service to use the outer context,
which I'm confident will not be disposed by the
garbage collector while the app is running.

Bug: 267758905
Test: Presubmit, device test to confirm everything works
Change-Id: Id8914a1ba954440999c65b91603ca22867938a97