Sanitize system route types to TYPE_UNKNOWN for non-system providers

Non-system route providers should not be able to publish routes of any
system route type (e.g. wired headset, bluetooth, etc). The routing
framework will treat any route from a non-system route provider with a
system route type as TYPE_UNKNOWN and log a warning.

Ideally, we should introduce a compat change on the next API bump to just
rethrow a SecurityException instead of switching the route type.

Bug: 347499404
Test: atest CtsMediaBetterTogetherTestCases and manually via
MediaRouting demo app
Flag: EXEMPT bugfix

Change-Id: I482b315fd3eba48a5b10e877fec3754e051826d4