Allow overrides in declare-release-config

A release config declaration may indiciate that one or more other
release configs should be applied before this one overrides them, so
that we don't have to manually keep common flags in sync.

Bug: b/313479515
Test: manual
Ignore-AOSP-First: Corresponding changeset is in AOSP
Merged-In: Ida444a5dbba578a36bd3607246fa14fc73b3f923
Merged-In: Ib7350500ae44adf4767aa7f9dbb8e71609fdd8c0
Change-Id: Ib7350500ae44adf4767aa7f9dbb8e71609fdd8c0