As an editor I want to see a list of all EntitySchemas in order to easily see what is available.

Problem:
Right now there is only a bot-maintained list of all Entity Schemas. In addition there is Special:AllPages but it only lists Entity Schemas by their ID and does not show labels and descriptions.
For Properties we have a dedicated SpecialPage at https://www.wikidata.org/wiki/Special:ListProperties

Screenshots/mockups:
TODO

BDD
GIVEN
AND
WHEN
AND
THEN
AND

Acceptance criteria:

• There is a SpecialPage that lists all available Entity Schemas by their label and ID.
• The list is sorted numerically by ID

Open questions:

• Should we also show the description?

Notes:

• This might need a dedicated table for getting the ID for numerical sorting. Currently no index exists that we could use for this.