[Task]: Skip source code submission for enterprise add-on versions

[diox]

Description

Part of Enterprise Add-ons project.

Follow-up for https://github.com/mozilla/addons/issues/14849

In devhub, source code submission step should be skipped if the distribution mechanism is "enterprise". It should not be possible to submit source code for such versions (including after upload when editing the version in devhub page)

If that's easier the step could be shown with a message explaining that source code submission is not required for this channel, with the form to submit source code disabled.

Acceptance Criteria

  ### Acceptance Criteria
  - [ ] Source code is not required for enterprise versions
  - [ ] It should not be possible to submit source code for enterprise versions

Checks

• [X] If the issue is ready to work on, I have removed the "needs:info" label.

┆Issue is synchronized with this Jira Task