Expressions: offer bezier in the language menu and auto-complete (#1884)

Add the helper to the expression editor's completions (syntax highlighting and auto-complete) and to the Expression Language menu's Interpolation group, so accepting it inserts the call parentheses like linear/ease.

crates/engine/src/cmd/expr_tools.rs

@@ -163,6 +163,8 @@ pub fn language_menu() -> Vec<(&'static str, Vec<(&'static str, &'static str)>)>
                 ("easeIn(t, tMin, tMax, value1, value2)", "easeIn(t, tMin, tMax, value1, value2)"),
                 ("easeOut(t, value1, value2)", "easeOut(t, value1, value2)"),
                 ("easeOut(t, tMin, tMax, value1, value2)", "easeOut(t, tMin, tMax, value1, value2)"),
+                ("bezier(t, value1, value2, [x1, y1, x2, y2])", "bezier(t, value1, value2, [x1, y1, x2, y2])"),
+                ("bezier(t, tMin, tMax, value1, value2, [x1, y1, x2, y2])", "bezier(t, tMin, tMax, value1, value2, [x1, y1, x2, y2])"),
             ],
         ),
         (

crates/ui-egui/src/panels/expr_editor.rs

@@ -111,6 +111,7 @@ pub const COMPLETIONS: &[&str] = &[
     "ease",
     "easeIn",
     "easeOut",
+    "bezier",
     "clamp",
     "random",
     "gaussRandom",