[Nexthop][m4062nhp] Add platform mapping and SAI agent wiring

[zackary-nexthop]

Pre-submission checklist

• I've ran the linters locally and fixed lint errors related to the files I modified in this PR. You can install the linters by running pip install -r requirements-dev.txt && pre-commit install
• pre-commit run

Summary

Adds the platform mapping for m4062nhp: M4062nhpPlatformMapping.h/.cpp.

Also wires m4062nhp into the SAI agent (cmake/AgentPlatformsSai.cmake, SaiPlatform.cpp, SaiPlatformInit.cpp) and adds the default m4062nhp agent.conf.

The input platform mapping CSV and JSON files are in a separate PR #1419.

Test Plan

• All 128 ports come up with correct GID/lane mapping, tested on an m4062nhp system.

[srikrishnagopu]

Please split the diff into three smaller diffs:

• platform mapping python tool changes
• csvs
• platform mapping changes to fboss

[zackary-nexthop]

Please split the diff into three smaller diffs:

• platform mapping python tool changes
• csvs
• platform mapping changes to fboss

@srikrishnagopu I've moved the CSV and JSON files to a separate PR (#1419). However I do not understand what you mean by the platform mapping python tool changes. If this is verify_generated_files.py, adding m4062nhp to it needs to be done along with the CSV changes for the CI to pass. The rest of the changes in that file are pre-commit lints. Let me know if I'm missing anything.

[meta-codesync]

@srikrishnagopu has imported this pull request. If you are a Meta employee, you can view this in D113787581.

[srikrishnagopu]

@zackary-nexthop I landed several changes today morning for this platform which is conflicting with this current diff. Can you rebase with latest FBOSS and resubmit it please ?

[facebook-github-tools]

@zackary-nexthop has updated the pull request. You must reimport the pull request before landing.

[zackary-nexthop]

@zackary-nexthop I landed several changes today morning for this platform which is conflicting with this current diff. Can you rebase with latest FBOSS and resubmit it please ?

@srikrishnagopu done!

[facebook-github-tools]

@zackary-nexthop has updated the pull request. You must reimport the pull request before landing.

[zackary-nexthop]

Closing as discussed offline. This is not required anymore, thanks to the new config driven model #1419 should be enough.
Will open a separate PR for oss/agent.conf.