[thread host] Update Leave method

[Irving-cl]

This PR updates the ThreadHost::Leave method.

This PR adds a parameter aEraseDataset to the method. This PR also implements this method for RcpHost. The implementation is consistent with the android implementation. The PR also adds a unit test for RcpHost::Leave.

[codecov]

Codecov Report

Attention: Patch coverage is 73.91304% with 24 lines in your changes missing coverage. Please review.

Project coverage is 46.16%. Comparing base (2b41187) to head (f42c814).
Report is 885 commits behind head on main.

Files with missing lines	Patch %	Lines
tests/gtest/test_rcp_host_api.cpp	81.63%	9 Missing ⚠️
src/ncp/rcp_host.cpp	75.75%	4 Missing and 4 partials ⚠️
src/ncp/ncp_host.cpp	0.00%	6 Missing ⚠️
src/dbus/server/dbus_thread_object_ncp.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2618      +/-   ##
==========================================
- Coverage   55.77%   46.16%   -9.62%     
==========================================
  Files          87      106      +19     
  Lines        6890    12707    +5817     
  Branches        0      921     +921     
==========================================
+ Hits         3843     5866    +2023     
- Misses       3047     6523    +3476     
- Partials        0      318     +318     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[sunytt]

LGTM 👍

[superwhd]

LGTM 👍