feat(core): use PathExt to unify env var resolution

This new implementation allows for expanding any environment variable so
it is not limited to just `~`, `$HOME`, `$Env:USERPROFILE` and
`$Env:KOMOREBI_CONFIG_HOME`.

It expands the follwing formats:
- CMD: `%variable%`
- PowerShell: `$Env:variable`
- Bash: `$variable`

I searched throughout the code base for path and migrate any code that
might need to PathExt::replace_env.

It is possible that I might have missed a few places due to my
unfamiliarity with the code base, so if you find any, please let me
know.

Most of the paths that needed this trait, are in:

- Clap arguments, and that was handled by #[value_parse] attribute and a
  helper function.
- SocketMessage and that was handled by custom deserialization with the
  help of serde_with crate

komorebi-bar/src/bar.rs

@@ -49,6 +49,7 @@ use komorebi_client::Colour;
 use komorebi_client::KomorebiTheme;
 use komorebi_client::MonitorNotification;
 use komorebi_client::NotificationEvent;
+use komorebi_client::PathExt;
 use komorebi_client::SocketMessage;
 use komorebi_themes::catppuccin_egui;
 use komorebi_themes::Base16Value;
@@ -500,13 +501,16 @@ impl Komobar {
                 let home_dir: PathBuf = std::env::var("KOMOREBI_CONFIG_HOME").map_or_else(
                     |_| dirs::home_dir().expect("there is no home directory"),
                     |home_path| {
-                        let home = PathBuf::from(&home_path);
+                        let home = home_path.replace_env();
+
+                        assert!(
+                            home.is_dir(),
+                            "$Env:KOMOREBI_CONFIG_HOME is set to '{}', which is not a valid directory",
+                            home_path
+                        );
+
+                        home
 
-                        if home.as_path().is_dir() {
-                            home
-                        } else {
-                            panic!("$Env:KOMOREBI_CONFIG_HOME is set to '{home_path}', which is not a valid directory");
-                        }
                     },
                 );