Add permission to shell for CTS test

This grants the shell app the SUGGEST_EXTERNAL_TIME permission needed
for the TimeManagerTest (CTS) to invoke the
TimeManager.suggestExternalTime() method during tests.

Bug: 184947690
Bug: 177079827
Test: See associated cts change
Merged-In: Ia1995ec9503dbd2b12e0b5b5f92a96e02f85beec
Change-Id: Ia1995ec9503dbd2b12e0b5b5f92a96e02f85beec