[ncp] add handling for unused properties to avoid warning logs

[Irving-cl]

This PR adds handling for some NCP properites.

Currently theere are some logs like:

2025-02-27T10:57:03.981495+08:00 otbr-agent[424273]: [CRIT]-NcpSpin-: Received unexpected response with (cmd:6, key:0), waiting (cmd:3, key:2353) for tid:3

2025-02-27T02:38:29.478937+00:00 rpi-4 otbr-agent[6900]: [WARN]-NcpSpin-: Received uncognized key: 5389
2025-02-27T02:38:29.479525+00:00 rpi-4 otbr-agent[6900]: [WARN]-NcpSpin-: Received uncognized key: 90
2025-02-27T02:38:29.480519+00:00 rpi-4 otbr-agent[6900]: [WARN]-NcpSpin-: Received uncognized key: 91

This PR adds handling for these properties to avoid these warning logs. For unsolicited notification cases, add case for these properties to avoid that they go to the default case and emit warnings.

[gemini-code-assist]

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Project coverage is 43.74%. Comparing base (2b41187) to head (44edbdb).
Report is 962 commits behind head on main.

Files with missing lines	Patch %	Lines
src/host/ncp_spinel.cpp	0.00%	7 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2740       +/-   ##
===========================================
- Coverage   55.77%   43.74%   -12.04%     
===========================================
  Files          87      110       +23     
  Lines        6890    13408     +6518     
  Branches        0      954      +954     
===========================================
+ Hits         3843     5865     +2022     
- Misses       3047     7238     +4191     
- Partials        0      305      +305     

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