[platform_manager][weutil][darwin48v] Add an eeprom offset for i2cDeviceConfigs, use it to fix darwin48v eeprom issues

[dzarista]

Summary

Currently, i2cDeviceConfigs do not have an option to pass in an eeprom offset, unlike idpromConfigs.

This is an issue on platforms such as darwin48v which have an i2cDeviceConfig eeprom that has a specific offset where the Meta format is stored.

To solve this, I've added an optional i32 eepromOffset variable to the i2cDeviceConfig. During platform exploration for i2cDeviceConfigs, this offset will be checked if it exists and the appropriate FbossEepromInterface object will be created. I've also modified the weutil ConfigUtils to check for this offset.

In ConfigValidator, I've added a check for i2cDeviceConfigs that requires isEeprom to be true if an eeprom offset is defiend.

Additionally, I've removed the fanspinner symlink generation from platform manager for darwin(48v) as it does not have a valid Meta eeprom.

Test Plan

On darwin(48v) -

platform_manager initializes and does not display errors related to the chassis eeprom or fanspinner eeprom.
weutil_hw_test passes.

[meta-codesync]

@RomanChoporov-Meta has imported this pull request. If you are a Meta employee, you can view this in D93255306.