Add "--cache" And "--config" Flags

[p0da]

Is your feature request related to a problem? Please describe. Currently the cache and config are held in $XDG_CACHE_HOME and $XDG_CONFIG_HOME respectively. However there seems to be no way to ensure that they are kept separate at custom locations specified on the CLI as the "basepath" flag combines them into one directory. Would you consider either replacing basepath with config and cache flags or adding config and cache flags that specify the path to the respective files? It seems like this was the intent in https://github.com/hrkfdn/ncspot/issues/65#issuecomment-488808239 but it instead resulted in --basepath.

Describe the solution you'd like Add --cache and --config.

[anuramat]

it would be nice to move userstate.cbor to cache home too :eyes: