Bluetooth: Shell: BR: Find HFP_HF records on HFP_AG side

Add a option `HFPHF` to find HFP HF SDP records from HFP AG side.

Add a SDP records discovery parameter `discov_hfphf` for this option.

Add a function `sdp_hfp_hf_user` to handle the discovery result.

Signed-off-by: Lyle Zhu <lyle.zhu@nxp.com>