[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] Create ports the way the Qumran4D SAI requires #1879
2. This (top of stack)

The Qumran4D SAI assigns the TM slot of a port created at runtime itself, as the lowest free index in the port's core. The agent builds the port's VOQ system port from the platform mapping's core port index, which can match only one creation order. Any other breakout fails when the agent creates the system port.

[system_port] Failed to create sai entity SystemPortSaiId(0): (ConfigInfo: (port_id: 430, switch_id: 0,
 attached_core_index: 0, attached_core_port_index: 19, speed: 400000, num_voqs: 8) ...): ITEM NOT FOUND

The new SYSTEM_PORT_CORE_INDEX_FROM_PORT feature, set only for Qumran4D, makes SaiSystemPortManager build a local interface port's system port from the core and core port index that the SAI reports for the port. It falls back to the platform mapping when the port does not exist yet. Recycle, management and eventor ports, remote system ports and the software SystemPort state are unchanged.

Test Plan

On a m4340nhp device, breaking a cage out to 2x400G, 4x200G or 8x100G brings all of its ports up, and they stay up across a warm boot. Without this change, the 2x400G breakout makes the hardware agent crash-loop with the error above. The changed files build in the OSS build.