[RFE] Add dedicated/simplified UI for containers' env vars

[joaquimrocha]

Current situation

If users want to edit a containers' env var, they need to change the respective resources' YAML.

Impact

Editing the YAML just for this can be cumbersome and lead to errors.

Ideal future situation

There's a simplified (key name -> value) editor that can be used just for changing the env vars.

Implementation options

TBD