floss: Add set-alias to btclient and API.

Adds support for changing the remote device alias. This also fixes the
BluetoothProperty conversions which were being done incorrectly
(off-by-one).

Bug: 196887190
Tag: #floss
Test: Built floss, verified alias can be updated in btclient.
Change-Id: I2c21feb9bb6763c4147997f349b06904c4bff20d