Can we have several environments for one Salesforce org ?

**General feedback**
Once I created a Code Builder env, I can't create a second one.
We have some orgs with several repositories, how are we supposed to work with them with only env ?
I couldn't find a way in Code Builder to switch to another repo.

Start by reviewing Code Builder's environment and repository workflow to understand why one Salesforce org permits only one environment. Define the expected behavior for multiple repositories, including how users switch between them; done means users can work with several repositories in the same org without recreating or losing environments.

Written by the indexing model from the issue text.