Code host integrations: always add utm_source
Created by: lguychard
Rel. #11447
Ensures we always add ?utm_source=platform_name
to links pointing back to the Sourcegraph instance from code host integrations, where the platform name is one of:
firefox-extension
, chrome-extension
, phabricator-integration
, bitbucket-integration
, gitlab-integration
As a side-effect, simplifies <OpenOnSourcegraph/>
and cleans up OpenInSourcegraphProps
to remove unused properties.