GitLab

 - Add ExecuteWrite to device to commit or abort changes
   in different characteristic
 - Add PrepareWriteValue() in remote characteristic API

A relevant patch is crrev.com/c/1065067

BUG=b:78650442
CQ-DEPEND=CL:1079668
TEST=Pass CtsVerifier test for reliable write on client side. Unittest.

Change-Id: Ibd1a68b9a3a1973c5287b46d41ec652f9d9f8352
Reviewed-on: https://chromium-review.googlesource.com/1065080
Commit-Queue: Qiyu Hu <qiyuh@google.com>
Reviewed-by: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Reviewed-by: Miao-chen Chou <mcchou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563140}