**Acceptance Criteria**
- On [[ https://meta.wikimedia.org/wiki/Special:Block | Special:Block ]], add a section under the username/IP input box for `Type`
- The options should be two radio buttons with labels and help description text.
- The top radio button, which should be selected by default' should read `Sitewide`. When a block is saved with this selected, the block should behave exactly as it does today.
- The second radio button should read `Partial`. When selected, a TagMultiselectWidget OOUI element should allow for admins to type up to 10 pages from which the user should be blocked from editing.
-- Page blocks can only be set for existing pages.
--- Validation should occur in the input field or via error message when the "block this user" button is pushed — whichever is simpler
-- Pages can be from any namespace, the user must type in the namespace and colon (e.g. `Template:Foobar`)
- [[ https://www.mediawiki.org/wiki/API:Block | API:Block ]] should be updated to allow a site-wide OR partial block and the partial block configuration (pages for now, namespaces in the future)