HackStudio: Add new multiline commit dialog

This new commit dialog features multi-line input and a line and column
indicator. A great improvement over the last one, if you ask me! :^)

Userland/DevTools/HackStudio/Dialogs/Git/GitCommitDialog.gml

@@ -0,0 +1,42 @@
+@GUI::Frame {
+    fill_with_background_color: true
+
+    layout: @GUI::VerticalBoxLayout {
+        spacing: 4
+        margins: [4, 4, 4, 4]
+    }
+
+    @GUI::Label {
+        text: "Enter commit message:"
+        text_alignment: "CenterLeft"
+        fixed_height: 20
+    }
+
+    @GUI::TextEditor {
+        name: "message_editor"
+    }
+
+    @GUI::Widget {
+        layout: @GUI::HorizontalBoxLayout
+        shrink_to_fit: true
+
+        @GUI::Label {
+            name: "line_and_col_label"
+            text: "Line: 1, Col: 0"
+            text_alignment: "CenterLeft"
+            fixed_height: 20
+        }
+
+        @GUI::Button {
+            name: "commit_button"
+            text: "Commit"
+            fixed_width: 75
+        }
+
+        @GUI::Button {
+            name: "cancel_button"
+            text: "Cancel"
+            fixed_width: 75
+        }
+    }
+}