Allow wikis to be named, instead of using a hash

[edg2s]

Use cases:

• It is often easy to forget the purpose of a wiki, especially if it is created without patches but with other custom settings
• In a workflow where you are created a small set of wikis for testing, it is difficult to keep track of which wiki does what, especially when pasting the links elsewhere. A name like "dt_2020_abtest_variant_a" would be much easier to use.

Cons:

• Long names make for long URLs and a variable width column on the frontpage
• Deleted wikis are still kept in the database meaning names could never be re-used

• We could scramble the names of deleted wikis, so that names could be re-used, this would be one way to solve Allow wikis to be redirected when deleting #171, but could also lead to confusing old links if a name is unintentionally re-used. Or we could prompt people when they are about to use the name of a deleted wiki.

Alternative approach:

• To avoid long URLs, we could store the names in a separate field, and just make them redirects to the hashes.