### Description
The Wikibase extension is installed on only a few Wiki projects, but plays a critical role for those communities. For example, the Wikidata REST API is not differentiated from the Wikibase API; it is simply the Wikibase API running against the Wikidata project.
The list of endpoints contained in this module is extensive, meaning that it is a huge list to include as part of the "Flat route" implementation. The documentation presented in the flat route structure is also duplicative, misleading, and incomplete compared to the "official" Wikibase REST API documentation, found here: https://doc.wikimedia.org/Wikibase/master/js/rest-api/
See flat route example: https://www.wikidata.org/wiki/Special:RestSandbox
The purpose of this work is to surface the high quality spec created by the Wikidata team (WMDE) through the REST Sandbox
### Conditions of acceptance
[] Create Wikibase v1 API module
[] Surface externally managed Wikibase OAD in the REST Sandbox for projects where it is enabled
[] Remove Wikibase routes from MediaWiki 'flat route' structure
[] Create a mechanism that allows setting a 'default' module within the REST Sandbox per wiki project
[] Update links on Wikidata to point to the REST Sandbox instead of the doc site
[] [Stretch/TBD] Redirect doc.wikimedia documentation (https://doc.wikimedia.org/Wikibase/master/js/rest-api/) to the Meta REST Sandbox (?)
OPEN QUESTIONS:
1. Where should the doc site redirect to, for cases where people might be seeking basic Wikibase information? Meta? Even though the extension is not installed there?