Update BS warning to follow through on action

The BS warning only had support for following through when a user
wanted to toggle battery saver. Refactors it slightly to be more
flexible in what it can do and also adds support for following
through when a user got here due to routine mode being modified.

Test: robotests pass, manual verification
Bug: 129696128
Change-Id: I1e18d37d069e265397e7f6fac2039a4ea748962b