As an editor I want to store a Schema I just prepared in order to share it with other editors.
**Mockup:**
{F27877324}
**BDD**
GIVEN the SpecialPage Special:NewSchema
WHEN clicking "Create"
THEN a new Schema entity is created
AND it is assigned an ID
AND the user is redirected to the new Schema page
**Acceptance criteria:**
[] new Schema entities can be created
[] new Schema entities go to their own namespace (Schema:)
[] new Schema entities are given incrementing unique IDs
[] Schema entity page contains the following data: ID, label, description and aliases in the user interface language
[] Label, description and alias in the user language are displayed in the header, or "there is no label" when there is no data in the user language
[] a new entry is added to Recent changes, watchlist and Schema page history with the text "Created a new Schema: label, description"
[] blocked users are not able to create a new Schema
**Open questions:**
* What's the entity ID format?