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 - Ensure that CCCD is added such that we can report the value change in
   CCCD to Android in OnNotificationStart/Stop()
 - Implement SendIndication() such that Android can call it

Bug: b:78593133
Test: Pass Android CtsVerifier test on server sending indication/notification
Change-Id: I8b1a4be6596555003d6d447b4518f37632a45370
Reviewed-on: https://chromium-review.googlesource.com/1119079
Commit-Queue: Qiyu Hu <qiyuh@google.com>
Reviewed-by: Luis Hector Chavez <lhchavez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572291}