[FeatureRequest] Dev Env Settings Window option to add unkown repository name

[janosmurai]

The user should be able to add a repository path to the Dev Env, which is located in a registry unknown to DEM.

Example

Prerequisite: The rust Docker Hub registry has not been added to DEM.

1. Run dem create test
2. On the Dev Env Settings Window, in the input field enter rust/rust:bookworm.
3. Press enter. The repo should be added to the Selected Tool Images.

The repo with the given tag should be also added to the available tool images to search from in the Dev Env Settings Window.

TBD: How to remove such an item from the list?

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For axem internal use only:
Jira: https://axem.atlassian.net/browse/DEM-285