Expose "Validate" endpoint in Kafka Connect UI

[yeikel]

Issue submitter TODO list

• I've searched for an already existing issues here
• I'm running a supported version of the application which is listed here and the feature is not present there

Is your proposal related to a problem?

While creating of changing the configuration for connectors, it is often valuable to validate the configuration first before attempting to submit it. The current UI does not expose that feature

Describe the feature you're interested in

We should add a "Validate" button next to the "Submit button" that calls the /validate/ endpoint of Kafka Connect

Describe alternatives you've considered

Option 1 : Call the API manually
Option 2: Create the connector and pause it afterwards (not ideal)

Version you're running

c8a8759

Additional context

No response