monitor/att: Add decoding support for GMCS

monitor/att: Add decoding support for GMCS

This adds decoding support for GMCS attributes.

< ACL Data TX: Handle 3585 flags 0x00 dlen 7
      ATT: Read Request (0x0a) len 2
        Handle: 0x0056 Type: Media Control Point Opcodes Supported (0x2ba5)
> ACL Data RX: Handle 3585 flags 0x02 dlen 9
      ATT: Read Response (0x0b) len 4
        Value: 33180000
        Handle: 0x0056 Type: Media Control Point Opcodes Supported (0x2ba5)
              Supported Opcodes: 0x00001833
                Play (0x00000001)
                Pause (0x00000002)
                Stop (0x00000010)
                Move Relative (0x00000020)
                Previous Track (0x00000800)
                Next Track (0x00001000)

Signed-off-by: Manika Shrivastava <manika.sh@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>