Add Bluetooth toggle prompts - framework

If permission review is enabled toggling bluetoth on or off
results in a user prompt to collect consent. This applies
only to legacy apps, i.e. ones that don't support runtime
permissions as they target SDK 22.

Also added a configuration resource which controls whether
permission review mode is enabled. By default it is not and
an OEM can change this via an overlay. For now we also keep
the old mechanism to toggle review mode via a build property
which is still used and will be removed when clients have
transitioned.

bug:28715749

Partial cherry-pick of core/res/res/values/{config,symbols}.xml only
Change-Id: I94c5828ad6c8aa6b363622a26ff9da4fc2e2fac7
(cherry picked from commit ac69be54)