custom Add width property for CustomMetricGroup

custom Add width property for CustomMetricGroup: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). I understand that for high level APIs (e.g. monitor<ResourceType ) it's easier for the library to calculate width dynamically. However for CustomMetricGroup may we have…

The task

I understand that for high level APIs (e.g. `monitor<ResourceType>`) it's easier for the library to calculate width dynamically. However for `CustomMetricGroup` may we have a `width` property?

Part of FineEnvs/MiMo-V2.6-RL-harbor-code.