GetCredentials queries the http.Request for X-Registry-.* headers and extracts the necessary authentication information for libpod operations, possibly creating a config file.

MakeXRegistryAuthHeader returns a map with the "X-Registry-Auth" header set, which can conveniently be used in the http stack.

MakeXRegistryConfigHeader returns a map with the "X-Registry-Config" header set, which can conveniently be used in the http stack.

RemoveAuthfile is a convenience function that is meant to be called in a deferred statement.