Implement remarkup custom control

Summary: Ref T2575. Adds "remarkup" control, which displays a remarkup control and uses the remarkup cache. Grants fields access to remarkup pipeline.

Test Plan:
{F35067}
{F35068}

Used DarkConsole to verify cache interaction with services.

Reviewers: hach-que, btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2575

Differential Revision: https://secure.phabricator.com/D5286

src/docs/userguide/maniphest_custom.diviner

@@ -44,8 +44,8 @@ Each array key must be unique, and is used to organize the internal storage of
 the field. These options are available:
 
   - **label**: Display label for the field on the edit and detail interfaces.
-  - **type**: Field type, one of **int**, **string**, **bool**, **select** or
-    **date**.
+  - **type**: Field type, one of **int**, **string**, **bool**, **select**,
+    **remarkup**, or **date**.
   - **caption**: A caption to display underneath the field (optional).
   - **required**: True if the user should be required to provide a value.
   - **options**: If type is set to **select**, provide options for the dropdown