Bluetooth: Add trust device feature.

Add set trust feature where the remote device is marked
as a trusted device for subsequent connection.

CRs-fixed: 523135

Change-Id: I9bde4d7dfe07d9d63b58a661ed2413f45501bd7b
Bluetooth: HID: Add support for Set Idle and Get Idle Commands

This patch provides an interface for application to send Set Idle
and Get Idle commands to remote HID Device. Support for these
two commands was missing from exisitng code, so existing code
design is reused to add support for these two commands.

Change-Id: I548362cc328498920b2dae740f1a76b2cc2d6a67
CRs-Fixed: 522511