Make EXTRA_IS_REFRESH for voicemail notification public

This extra is added in ag/2333070 to let the dialer know if a
notification should be silent since the user has alread been notified

Change-Id: I9a0fd901d76d6830631b88a9addde3efe89e5407
Fixes: 62202833
Test: manual - leave voicemail, toggle airplane mode.
1 file changed