[aevnsvi]

Adds unit and component tests for how a repository's served URLs are found, the shared create flow, the repository form, the file repository create and edit pages, and the build stamp check.

• repositoryDistributions: repository-, publication- and version-bound distributions with the server's base_url, the paged scan across pages, a failed load rejecting with a readable message instead of an empty list, the not-served rule for deb.
• File Distributions tab: the base_url and the manifest line built from it.
• createRepository: blocked before the first POST when the name or base path is taken or cannot be checked; repository then distribution in order; a refused distribution leaves the repository alone with the server's reason, no retry, no rollback.
• Repository form: create-distribution box only on create and unticked, reserved base path prefixes, retained versions, double click on Save.
• File repository pages: empty retained versions saves null, the server's refusal of 0 is shown, one POST for a double click, editing sends one PUT and creates nothing.
• Build stamp: a malformed PULP_UI_COMMIT stops loading the settings module with a message naming the variable. The node test project also collects tests under config/.
• The list handler of the test utilities can filter rows the way a server filter does.

No production source is changed. The suite also passes in shuffled order.