File structure of client configuration directories

[ErikBjare]

On Linux, all user-level config files should be stored in a subdirectory of $XDG_USER_CONFIG (defaults to $HOME/.config) according to XDG spec.

Currently we have an issue where we don't place the configuration files of different modules in a consistent manner. We currently use appdirs for this in a lot of places, we should consider putting a function get_global_config_dir() and get_config_dir(module_name) in the aw-core package which is used everywhere. We might also want a get_log_dir(), even though it might end up only being used in aw_core.log.

We might also want to consider $XDG_DATA_HOME (defaults to $HOME/.local/share) for data such as databases (sqlite etc.) managed by aw-server. We might even want to consider $XDG_CACHE_HOME in case we ever want to cache some dataviews presented by aw-server for instance (which is likely).

[ErikBjare]

Fixed for logs in: ActivityWatch/aw-core#13

[ErikBjare]

Done with the barrage of unified-dirs PRs.