Disable communal touch handler when not on keyguard

After ag/32431678, isCommunalAvailable may be true when keyguard isn't
showing. Avoid grabbing touches in this case by also checking if
keyguard is showing in the touch handler.

Also had to rename existing function in KeyguardInteractor to resolving
naming conflict when calling methods from java. That class currently has
two methods in java called "isKeyguardShowing()" - one for the flow and
one for a getter which returns a boolean. This renames the getter to
disambiguate from the flow.

Bug: 392969914
Test: atest CommunalTouchHandlerTest
Flag: EXEMPT no-op when v2 flag is disabled
Change-Id: I97cc393bb079ee8bf679d43301e3da1959689301