fix: Improve adapter management

[dominikriemer]

Purpose

Add various smaller improvements to the StreamPipes Connect user interface and adapter management:

• Use a progress bar in the GuessSchema component
• Add a timeout to the Kafka onSchemaRequested method
• Poll from latest instead of beginning when requesting a schema in the Kafka adapter
• Add a progress indicator which replaces the adapter status icon when an adapter operation is in progress

Remarks

PR introduces (a) breaking change(s): no

PR introduces (a) deprecation(s): no