Add namespace to create environment form

[gabalafou]

Fixes one half of #307.

Description

This pull request shows the namespace on the form/tab to create a new environment.

Pull request checklist

• [x] Did you test this change locally?
• [ ] Did you update the documentation (if required)?
• [x] Did you add/update relevant tests for this change (if required)?

[gabalafou]

I'm not sure this looks the way we want:

Side comment: in that screenshot I'm using the MUI TextField component in disabled mode. That seemed like the most straightforward way to add the namespace to the page. However, the colors on disabled text fields in MUI are low contrast, so I think I should probably re-implement the namespace as something else.

[gabalafou]

@smeragoel when you get a chance could you review this?

[smeragoel]

@gabalafou and I discussed this issue and we decided that we're gonna see how much effort it is to customize the input component to match the designs and then we can decide the way forward

[gabalafou]

Given the conversation in today's planning meeting, I reverted my last commit in favor of using the MUI TextField component without customization

[gabalafou]

The Playwright test is probably a legit failure. Need to investigate.

[gabalafou]

Merged since all checks pass!