Quay config-app should provide config options of USERFILES_LOCATION and USERFILES_PATH

Description:

This is a Quay feature request about Quay-config app, now Quay config.yaml support the configurations of "USERFILES_LOCATION" and "USERFILES_PATH", and when users upload DockerFiles to build image, quay will upload it to the storage location defined in config.yaml, but these two configurations are not exposed via Quay-config App.

Suppose when quay customer deploy Quay with two or more Storage Locations, and use default config.yaml configurations, but none of them has Location ID named "default". then when Quay customers upload DockerFile to build image, will hit error "KeyError: 'default'"

Suggest add config options USERFILES_LOCATION and USERFILES_PATH on Quay-Config app, and update Quay docs to let customers know how to use.

Quay default Config.yaml

USERFILES_LOCATION: default

USERFILES_PATH: userfiles/