Rename `Component::component_type` to improve clarity

[tiyash-basu-frequenz]

What's needed?

The way this field is named in the Component message is misleading:

frequenz-api-common/proto/frequenz/api/common/v1/microgrid/components/components.proto

Lines 134 to 135 in 5265439

	// The metadata specific to the component category type.
	ComponentCategoryMetadataVariant category_type = 5;

The field name was left as is since older times, and it probably needs to be updated to reflect its latest type.

Proposed solution

We could just rename it to component_metadata.

Use cases

No response

Alternatives and workarounds

No response

Additional context

No response

[llucax]

As I said in #249, I think calling it category_specific_xxx is more clear (where xxx is one of {metadata,info,fields,details}¹), as a component is the sum of the general {metadata,info,fields,details} in Component + the category-specific {metadata,info,fields,details} in Battery, Inverter, etc.. depending on the category of the component.

If we don't want to add a suffix {metadata,info,fields,details} to Battery, Inverter, etc., I think I could even live with calling this field simply category_specific.

// Metadata specific to a microgrid component.
message CategorySpecific {
  oneof category {
    frequenz.api.common.v1.microgrid.components.Battery battery = 1;
    frequenz.api.common.v1.microgrid.components.EvCharger ev_charger = 2;
    frequenz.api.common.v1.microgrid.components.Fuse fuse = 3;
    frequenz.api.common.v1.microgrid.components.GridConnectionPoint grid = 4;
    frequenz.api.common.v1.microgrid.components.Inverter inverter = 5;
    frequenz.api.common.v1.microgrid.components.VoltageTransformer voltage_transformer = 6;
  }
}

// Microgrid electrical component details.
message Component {
  // ...

  // The component category. E.g., Inverter, Battery, etc.
  ComponentCategory category = 4;

  // The fields that are only present for this component's category.
  CategorySpecific category_specific = 5;

  // ...
}

category = component.category_specific.WhichOneOf("category")
if category == "battery":
    battery = component.category_specific.battery

Footnotes

1. Again, my personal favorite is info if we are going for a suffix. ↩