fix(grpc-sdk): module connection not re-established after core shutdown

[kkopanidis]

With the current implementation, should the core module shutdown, the modules do not attempt to reconnect to it. If they try to set config etc, they should re-establish connection but without properly updating their state. At the same time, the module change watcher won't be restarted and the module won't be made aware of any changes.

This PR fixes this issue, by making sure that once the core connection drops, the modules begin trying to reconnect, and restart the watchers upon successful connection.

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other (please describe)

Does this PR introduce a breaking change?

• Yes
• No

The PR fulfills these requirements:

• It's submitted to the main branch
• When resolving a specific issue, it's referenced in the PR's description (e.g. fix #xxx, where "xxx" is the issue number)

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature

Other information: