Restrict the namespaces Kaoto can use for deployment on cluster

[tplevko]

Describe the Bug

There is currently no way or users to know, whether the namespace specified in Kaoto exists - it would be useful to have this either restricted, or have a way for the user to be able to create the namespace (this might be out of scope).

The current state allows users to specify non-existing namespaces, which in case there is a typo in the specified namespace can be difficult to figure out. Also the "deployment" to this non-existing namespace is possible, even though the deployment is not created.

Steps to Reproduce the Bug or Issue

1. open settings modal
2. specify user namespace where the deployment should run
3. in case the namespace doesn't exist - the user can trigger deployment, with error thrown only in the backend

Screenshots or Videos

No response

Platform

• OS: [e.g. macOS, Windows, Linux]
• Browser: [e.g. Chrome, Safari, Firefox]
• Version: latest