Implement missing ICoreModule methods

[sentry]

This PR resolves a FatalErrorException occurring because Miraheze\CreateWiki\Helpers\ManageWikiCoreModule did not implement three abstract methods required by the Miraheze\ManageWiki\ICoreModule interface.

The ICoreModule interface in WikiOasis/ManageWiki was updated to include getDeploymentGroup(), setDeploymentGroup(), and getDeploymentGroupOptions(). However, ManageWikiCoreModule in WikiOasis/CreateWiki was not updated concurrently, leading to a runtime error when the class was instantiated.

This fix adds stub implementations for these three methods to ManageWikiCoreModule:

• getDeploymentGroup() now returns an empty string ''.
• setDeploymentGroup() is implemented as a no-op.
• getDeploymentGroupOptions() now returns an empty array [].

These stub implementations satisfy the interface contract without introducing new functionality, as the CreateWiki extension's RemoteWiki context does not directly utilize these deployment group concepts.

Fixes MEDIAWIKI-2B9

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