Build: Add the Blubber config file
Build: Add the Blubber config file

This depends on the work being done in PR #1148.

Bug: T223953

cscott/restbase,wikimedia/restbase,wikimedia/mediawiki-services-restbase,wikimedia/mediawiki-services-restbase,d00rman/restbase,Pchelolo/restbase,cscott/restbase,Pchelolo/restbase,milimetric/restbase,d00rman/restbase,wikimedia/restbase,milimetric/restbase