[marif-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

PR commit stack:

1. [Nexthop][m4340nhp] Add the platform mapping #1876
2. [Nexthop][m4340nhp] "asic_config_v3" - Add the Qumran4D ASIC and the m4340nhp config #1877
3. This (top of stack)

Add the m4340nhp default agent.conf, qsfp.conf, led.conf and num_hw_agents. The agent.conf embeds the SDK config that #1877 generates. It has no nodeMac for the local DSF node, because the MAC differs per unit, and #1881 fills it in at boot.

Test Plan

On a m4340nhp device, fboss_init installs these configs, and the agents start and bring up all 64 front-panel ports.