[host] update directory name and namespace from ncp to host

[Irving-cl]

This PR changes the source directory name and namespace 'ncp' to 'host'.

The namespace and directory name is very confusing because under the namespace we have code and modules for both NCP & RCP case. The name was called 'ncp' since a long time ago. Now let's update.

[codecov]

Codecov Report

Attention: Patch coverage is 85.48387% with 9 lines in your changes missing coverage. Please review.

Project coverage is 43.63%. Comparing base (2b41187) to head (0c27123).
Report is 916 commits behind head on main.

Files with missing lines	Patch %	Lines
tests/gtest/test_rcp_host_api.cpp	88.88%	5 Missing ⚠️
src/dbus/server/dbus_thread_object_ncp.cpp	0.00%	2 Missing ⚠️
src/agent/application.cpp	66.66%	1 Missing ⚠️
src/dbus/server/dbus_agent.cpp	66.66%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2665       +/-   ##
===========================================
- Coverage   55.77%   43.63%   -12.14%     
===========================================
  Files          87      106       +19     
  Lines        6890    13254     +6364     
  Branches        0      953      +953     
===========================================
+ Hits         3843     5784     +1941     
- Misses       3047     7163     +4116     
- Partials        0      307      +307     

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[zhanglongxia]

LGTM

[superwhd]

LGTM 👍

Thanks for fixing this tech debt!

[abtink]

👍