Update subtitle in the widget area API to accept component or text as parameter and use it for KMW area

[zutigrm]

Feature Description

Following the implementation of 8895, we need to expand on Widget area API, to allow passing the component for subtitle. As in this issue, subtitle of the KMW widget area should be conditionally hidden if key metrics is not setup yet per new figma design

Initial implementation idea can be found in these commits: here, here and here, as starting point perhaps

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Acceptance criteria

• Widget area should support conditional display of subtitle
• KMW area subtitle should be shown only when KM has been setup as per new figma design

Implementation Brief

Test Coverage

QA Brief

Changelog entry