MINOR: proxy: Add fe_name/be_name fetchers next to existing fe_id/be_id

MINOR: proxy: Add fe_name/be_name fetchers next to existing fe_id/be_id

These 2 patches add ability to fetch frontend/backend name in your
logic, so they can be used later to make routing decisions (fe_name) or
taking some actions based on backend which responded to request (be_name).
In our case we needed a fetcher to be able to extract information we
needed from frontend name.