Adding `Type()` to Plugin interface

[elevran]

Currently (scheduler) Plugins support a Name() function.
The Name effectively serves as their type (e.g., see config proposal #881).
Further, there is no support for instance specific name when the system is configured with multiple plugins of the same type (e.g., Prefix scorer in disaggregated P/D).

What would you like to be added:

• Extend the Plugin interface type with Type() string while repurposing the current Name() function to indicate the specific instance name.

Why is this needed:

• support multiple Plugins of the same type with different instance names (e.g., for logging)
• align configuration file semantics to create and use named instance of a specific type

Alternatives:

• can retain the current Name() and add an (e.g.) InstanceName() to minimize the code changes
• use Kind() (or GKV if so inclined) for Kubernetes alignment
• extend "Name()" to be a "namespaced name" in the format of name / instance (i.e., overload the name to include both the type and instance)

Would be happy to make that change if acceptable.

CC: @ahg-g @kfswain @nirrozenbaum @shmuelk

[ahg-g]

Make sense to me.

[elevran]

If acceptable, please assign to me.

[nirrozenbaum]

/assign @elevran

[nirrozenbaum]

I recommend splitting the task to two different commits (or even two PRs).
first is to rename existing Name to Type.
second is to add additional field.
this could get confusing and separating would help avoiding human errors (both in coding and in reviewing)