T86875: Bug fix: Load specs from x-restbase-paths as well
T86875: Bug fix: Load specs from x-restbase-paths as well

It seems the parsing and loading of x-restbase-paths stanza has been
left out accidentally. This commit brings it back. Also, add a check in
handlePaths() to ensure there are paths to be followed.

Pchelolo/restbase,wikimedia/mediawiki-services-restbase,d00rman/restbase,inverno/restbase,physikerwelt/restbase,milimetric/restbase,Krenair/restbase,wikimedia/mediawiki-services-restbase,inverno/restbase,wikimedia/hyperswitch,milimetric/restbase,eevans/restbase,d00rman/restbase,Pchelolo/restbase,eevans/restbase,wikimedia/restbase,gwicke/restbase,physikerwelt/restbase,cscott/restbase,Krenair/restbase,wikimedia/restbase,gwicke/restbase,cscott/restbase