Add ResolverDialogLayout widget

Currently it's not used anywhere in frameworks but it's being added to
be used by a desktop RRO overriding ResolverActivity's layout.

Bug: 417351080
Test: Manual testing && atest com.android.internal.app.ResolverActivityTest
  running on a desktop image with the RRO overriding ResolverActivity's
  layout to use ResolverDialogLayout.
Flag: NONE not possible, the user side will be flag protected.

Change-Id: Ia23fde4842135859c96eea54269aa84f8d7c234e