Allow slug specification on new plugin upload

[dd32]

When uploading plugins to WordPress.org, it's no uncommon that people want to customise the slug.

Currently the slug is derived from the plugin name, and changing it requires manual action by the reviewers BEFORE the plugin is approved.

It's not uncommon for uploaders to ignore the post-upload email, and to request the slug be changed once they get the approved email.

It would be beneficial if after uploading a new plugin, the uploader is presented with information about the plugin, including the slug, and given a chance to update the slug then-and-there (and perhaps to delete/abort the upload if they've uploaded the incorrect thing..)

[dd32]

In 12617:

Plugin Directory: Allow for the plugin slug to be changed by the uploader *for new plugins*.

The slug can only be changed once by the submitter.

This removes the need for the plugin author to email us post-upload to request the slug be changed, in many cases.

Hopefully this will also reduce instances of an author requesting a slug change post-approval.

See #6107.

[dd32]

In 12621:

Plugin Directory: Only new plugins can change their slug, not once they're pending.

This was enforced by the endpoint, but not the UI.

See [12617].
See #6107.

[dd32]

Based on audit logs, it appears that some developers are still attempting to change it to their existing slug. No idea why.. doesn't cause any issue though.

Others appear to be using it without issue.

One potential pain-point is that the plugin authors are not having their textdomain set to the new slug in the ZIPs that are reviewed. As a result, during review this will get flagged as a 'These must match'. In some cases their textdomain is set to their previous slug, in others, it's set to something entirely incorrect.

[dd32]

In 12815:

Plugin Directory: Don't underline a.button links.

In [12617] I added CSS to skip underlines on a.dashicon, but in doing so I created a duplicate CSS rule which allowed underlining a.button.

See #6107.

[dd32]

Closing as fixed for now, we can iterate in new tickets for changes to the functionality.