client/player: Add support for custom preset

client/player: Add support for custom preset

This adds support for a custom preset which asks the user to enter its
configuration:

[bluetooth]# endpoint.presets 00002bc9-0000-1000-8000-00805f9b34fb custom
[Codec] Enter frequency (Khz): 48
[Codec] Enter frame duration (ms): 10
[Codec] Enter channel allocation: 0x000000003
[Codec] Enter frame length: 100
[QoS] Enter Target Latency (Low, Balance, High): Low
[QoS] Enter SDU Interval (us): 10000
[QoS] Enter Framing (Unframed, Framed): Unframed
[QoS] Enter PHY (1M, 2M): 2M
[QoS] Enter Max SDU: 200
[QoS] Enter RTN: 3
[QoS] Enter Max Transport Latency (ms): 20
[QoS] Enter Presentation Delay (us): 10000