Add editor: convert to sentence case (#35015)

This PR adds an `editor: convert to sentence case` action.

I frequently find myself copying branch names and then removing the
hyphens and ensuring the first letter is capitalized, and then using the
result text for the commit message.

For example:

<img width="927" height="482" alt="image"
src="https://github.com/user-attachments/assets/adf14a37-a92e-44df-8c0e-267b5c7677fb"
/>

You can achieve this with a combination of other text manipulation
commands, but this action makes it even easier.

Also, moved `toggle_case` down into the area where all other commands
internally using `manipulate_text` are located.

Release Notes:

- Added `editor: convert to sentence case`

crates/editor/src/editor.rs

@@ -10878,17 +10878,6 @@ impl Editor {
         });
     }
 
-    pub fn toggle_case(&mut self, _: &ToggleCase, window: &mut Window, cx: &mut Context<Self>) {
-        self.manipulate_text(window, cx, |text| {
-            let has_upper_case_characters = text.chars().any(|c| c.is_uppercase());
-            if has_upper_case_characters {
-                text.to_lowercase()
-            } else {
-                text.to_uppercase()
-            }
-        })
-    }
-
     fn manipulate_immutable_lines<Fn>(
         &mut self,
         window: &mut Window,
@@ -11144,6 +11133,26 @@ impl Editor {
         })
     }
 
+    pub fn convert_to_sentence_case(
+        &mut self,
+        _: &ConvertToSentenceCase,
+        window: &mut Window,
+        cx: &mut Context<Self>,
+    ) {
+        self.manipulate_text(window, cx, |text| text.to_case(Case::Sentence))
+    }
+
+    pub fn toggle_case(&mut self, _: &ToggleCase, window: &mut Window, cx: &mut Context<Self>) {
+        self.manipulate_text(window, cx, |text| {
+            let has_upper_case_characters = text.chars().any(|c| c.is_uppercase());
+            if has_upper_case_characters {
+                text.to_lowercase()
+            } else {
+                text.to_uppercase()
+            }
+        })
+    }
+
     pub fn convert_to_rot13(
         &mut self,
         _: &ConvertToRot13,