Move media filtering from NVHM to NotificationFilter

In addition, using the same inspection code as used by MediaDataManager
to determine when an SBN is a media notification.

Bug: 156928028
Test: manual - played audio with GPM and checked that notification
didn't appear.
Test: manual - played Support V7 Demo app and checked that notification
didn't appear.
Test: manual - `adb shell dumpsys activity service com.android.systemui/.SystemUIService NotifListBuilderImpl`
and check that GPM notification doesn't appear in list.

Change-Id: Ie670ac7c6d5f50489a8fc5670258d4eac030e41d