add special casing for repositoryQuery `org:<org-name>` in github extsvc
Created by: kzh
This pull request adds special casing to repositoryQuery
inputs with the format org:<org-name>
in the GitHub external service config. For these inputs, the GitHub org repositories endpoint /orgs/<org-name>/repos
will be called instead of the GitHub advanced repository search endpoint /search/repositories
. This is preferred due to the limitations (1k results limit, small rate limit, etc) of the search endpoint.