fix(workspaces): rewrite module to fix several small issues

Rewrites the module code to be better structured, in a similar pattern to the launcher. The code is now more robust and more maintainable, yay!

Fixes #705

Fixes an issue with moving favourite workspaces.

Fixes an issue with workspace visible state being incorrect.

Fixes an issue where the `inactive` class looked at hidden instead of closed favourites.

src/modules/workspaces/button_map.rs

@@ -0,0 +1,77 @@
+use super::button::Button;
+use crate::clients::compositor::Workspace;
+use std::collections::HashMap;
+use std::ops::{Deref, DerefMut};
+
+#[derive(Debug, Clone, Eq, PartialEq, Hash)]
+pub enum Identifier {
+    Id(i64),
+    Name(String),
+}
+
+/// Wrapper around a hashmap of workspace buttons,
+/// which can be found using the workspace ID,
+/// or their name for favourites.
+pub struct ButtonMap {
+    map: HashMap<Identifier, Button>,
+}
+
+impl ButtonMap {
+    pub fn new() -> Self {
+        Self {
+            map: HashMap::new(),
+        }
+    }
+
+    /// Gets the button for a workspace,
+    /// checking the map for both its ID and name.
+    pub fn find_button_mut(&mut self, workspace: &Workspace) -> Option<&mut Button> {
+        let id = Identifier::Id(workspace.id);
+
+        if self.map.contains_key(&id) {
+            self.map.get_mut(&id)
+        } else {
+            self.map.get_mut(&Identifier::Name(workspace.name.clone()))
+        }
+    }
+
+    /// Gets the button for a workspace,
+    /// performing a search of all keys for the button
+    /// with the associated workspace ID.
+    pub fn find_button_by_id(&self, id: i64) -> Option<&Button> {
+        self.map.iter().find_map(|(_, button)| {
+            if button.workspace_id() == id {
+                Some(button)
+            } else {
+                None
+            }
+        })
+    }
+
+    /// Gets the button for a workspace,
+    /// performing a search of all keys for the button
+    /// with the associated workspace ID.
+    pub fn find_button_by_id_mut(&mut self, id: i64) -> Option<&mut Button> {
+        self.map.iter_mut().find_map(|(_, button)| {
+            if button.workspace_id() == id {
+                Some(button)
+            } else {
+                None
+            }
+        })
+    }
+}
+
+impl Deref for ButtonMap {
+    type Target = HashMap<Identifier, Button>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.map
+    }
+}
+
+impl DerefMut for ButtonMap {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.map
+    }
+}