Draft: (WIP) Refactors and redesign for the daemon and common library

If merged, a part of the code within the flatsync-cli and libflatsync-common crates will be (re)written to:

• Make the uploaded JSON more useful (with remote information, detailed ref information, installation paths, etc.)
• Place common structs and traits into the libflatsync-common trait, making it possible for the CLI and GUI applications to make use of the serialized data easily and consistently
• Move associated functions around to make the code easier to understand

Example JSON on GitHub Gists: https://gist.github.com/rmnscnce/c8aa1476cb82df210757e2510a41de0c Example diff JSON for synchronization: https://gitlab.gnome.org/-/snippets/5564

TODOs:

• Use the libflatsync-common crate to share common functionality
• Implement installation and update in CLI and DBus daemon (fixes #9 (closed)) (ongoing)
• Handle errors properly