refactor: use k8s_service_info lib instead of SDI

[DnPlas]

Use the k8s_service_info for receiving the MLMD GRPC Service info instead of using the SDI, as it will stop being supported soon.

Fixes #76

NOTE for reviewers:

• I have added a component for wrapping the k8s service info requirer because we need to:

1. Have a way to return a status based on the relation conditions
2. Because there is no other way to do logic that prevents errors in the init method of the charm. For instance, it would be weird to have a try/catch in the init method for ensuring the required relation is established.

• Also note that this component could be placed in chisme, BUT that requires us to put charm libraries in the package, which is under discussion by the team.

Testing instructions

1. Deploy the charm in this branch
2. Deploy mlmd from channel latest/edge with trust
3. Relate both charms
4. Verify both charms go to active and idle

Test upgrade path

Because this charm was recently refactored from podspec to sidecar pattern, there will no be a migration from its previous stable version.

[ca-scribner]

Created canonical/charmed-kubeflow-chisme#94 to capture the discussion about how we could reuse code like the Component here that needs a charm library

[ca-scribner]

tiny issue otherwise lgtm

[orfeas-k]

Approving since the last comment @ca-scribner had is resolved now.

[DnPlas]

Approving since the last comment @ca-scribner had is resolved now.

Thanks @orfeas-k ! It looks like @ca-scribner has to approve it as he requested changes ;(

[DnPlas]

Approving since the last comment @ca-scribner had is resolved now.

Thanks @orfeas-k ! It looks like @ca-scribner has to approve it as he requested changes ;(

Dismissing @ca-scribner as the change he requested was very small and I did the change. Thanks both for the reviews!

The request was to change a duplicated line, which I did. This is a small enough change to not require another review.

[ca-scribner]

👍 ty!