Grant/revoke legacy "Storage" permissions.

The new isolated storage model we're building in Q introduces new
strongly-typed media permissions which replace the broad "Storage"
runtime permission.

That legacy "Storage" permission is marked as being "removed", and
it also splits into the new media permissions, but apps are confused
when they request the "Storage" permission, which no longer appears
as granted when the user accepts the new split media permissions.

After discussing with the permissions team, the best short-term
solution is to add special-case logic that grants the legacy
permissions when *any* of the new media permissions have also been
granted.  Only when the user revokes *all* of the new media
permissions is the legacy permission then revoked.  (MediaProvider
is already internally filtering the relevant content based on what
new media permissions the caller holds.)

Bug: 121227859
Test: manual
Change-Id: Ic87f7f93a816e91f7189509386255a260378c255