Implement admin/moderation tools/roles

[s-ludwig]

Should allow chosen persons to do things like manual user management, editing packages and transferring package ownership.

[wilzbach]

Maybe solvable with #150

[MartinNowak]

From #368 (comment)

There should be tools for admins (Ban Account, Shadow Ban Account, Delete Package), but also for users (Report Package, Report User)

As in the recent few cases of spammers (see e.g. #292) I think this is a much needed feature

[schveiguy]

More spam came to the registry (https://forum.dlang.org/post/rxsvumgfzppqwmubjivc@forum.dlang.org/). The only mechanism to delete spam is for the owner of the server (@s-ludwig ) to delete it by hand.

This kind of functionality needs to be in this server. I didn't realize there were no administrative pages for this. I don't know what other admin features exist, but we shouldn't have the entire ecosystem of D projects only accessible to one person.

[MartinNowak]

Spam Filter
#370