Retrieve and expose microgrid metadata

[leandro-lucarella-frequenz]

What's needed?

The microgrid API added a call to retrieve microgrid metadata. The metadata so far includes the microgrid ID and location (expressed in longitude and latitude). We need to expose that metadata in the SDK.

Proposed solution

• Expose the new GetMetadata gRPC call and its new associated types.
• Retrieve the metadata when connecting to the microgrid in the ConnectionManager
• Expose the ID and location, probably directly as a new attributes of the ConnectionManager: sdk.microgrid.get().id and sdk.microgrid.get().location
• Calculate the timezone of a microgrid based on the location and expose it too. This can be easily done in python using the timezonefinder package.
• Expose grid connection limits #360

Use cases

No response

Alternatives and workarounds

• Instead of exposing the attributes directly in the ConnectionManager, we could add a sdk.microgrid.get().metadata object and put the metadata there.
• We could not expose the timezone in the SDK and let users do the conversion themselves.

Additional context

• Add new RPC to return the microgrid metadata frequenz-api-microgrid#30
• https://github.com/frequenz-floss/frequenz-api-microgrid/blob/v0.x.x/proto/frequenz/api/microgrid/microgrid.proto

[llucax]

Blocked on #412