Use an intent action to launch MainActivity instead of class reference to DialtactsActivity.

We can't just replace DialtactsActivity with MainActivity because a circular dependency would be created. Instead create a new dialer-specific "main" intent action and use it.

Bug: 109931227
Test: manual
PiperOrigin-RevId: 199868961
Change-Id: I0ef72ed418280eeb64ea1ea854d215093b0dba27
2 files changed