Improve form validation for TLS during input creation

When defining an input with optional TLS (e.g. OpenTelemetry-gRPC): If I select Allow Insecure Connections = false but fail to supply certificate and key I can still launch the input. However, an error toast immediately pops up, when we validate the inconsistent configuration in the backend.

The launch button should be disabled if validations are going to fail; and missing / invalid input fields should be highlighted.