Don't hide last symbol under the scrollbar (#11696)

This PR adds an extra scrollbar-wide margin to the right side of the
editor. This prevents hiding the last character under the scrollbar.

Fixes #7098

Release Notes:

- Fixed hiding of the last character under the scrollbar (#7098).

crates/editor/src/editor.rs

@@ -11082,7 +11082,7 @@ impl Render for Editor {
                 background,
                 local_player: cx.theme().players().local(),
                 text: text_style,
-                scrollbar_width: px(13.),
+                scrollbar_width: EditorElement::SCROLLBAR_WIDTH,
                 syntax: cx.theme().syntax().clone(),
                 status: cx.theme().status().clone(),
                 inlay_hints_style: HighlightStyle {