[infra if] add platform infra if module

[Irving-cl]

This PR adds the InfraIf module on the host side.

This is to support border routing for NCP case. See this #2398 (comment) for the whole picture of this series of changes.

In this PR, InfraIf module only implements SetInfraIf method. This method is intended to be called by NcpHost during initialization or through ThreadHost API (for example, for the android case, where the infra if is ready later). This method will initialize the infra if and the border routing module on NCP.

This PR adds a unit test to verify the InfraIfDependency is called correctly.

[codecov]

Codecov Report

Attention: Patch coverage is 58.97436% with 32 lines in your changes missing coverage. Please review.

Project coverage is 45.75%. Comparing base (2b41187) to head (2836f97).
Report is 822 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ncp/posix/infra_if.cpp	52.72%	24 Missing and 2 partials ⚠️
tests/gtest/test_infra_if.cpp	73.91%	6 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2501       +/-   ##
===========================================
- Coverage   55.77%   45.75%   -10.03%     
===========================================
  Files          87      102       +15     
  Lines        6890    11971     +5081     
  Branches        0      876      +876     
===========================================
+ Hits         3843     5477     +1634     
- Misses       3047     6203     +3156     
- Partials        0      291      +291     

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[superwhd]

LGTM overall with minor suggestions

[abtink]

👍