This also factors the config questions into a state based mechanism so
a backend can be configured using the same dialog as rclone config but
remotely.
Restructuring of config code in v1.55 resulted in config
file being loaded early at process startup. If configuration
file is encrypted this means user will need to supply the password,
even when running commands that does not use config.
This also lead to an issue where mount with --deamon failed to
decrypt the config file when it had to prompt user for passord.
Fixes#5236Fixes#5228
This splits config.go into ui.go for the user interface functions and
authorize.go for the implementation of `rclone authorize`.
It also moves the tests into the correct places (including one from
obscure which was in the wrong place).
