Remove CallExpression support (#6639)

Users MUST use keyword call syntax now.

Closes https://github.com/KittyCAD/modeling-app/issues/4600

e2e/playwright/feature-tree-pane.spec.ts

@@ -3,7 +3,7 @@ import * as fsp from 'fs/promises'
 
 import { expect, test } from '@e2e/playwright/zoo-test'
 
-const FEATURE_TREE_EXAMPLE_CODE = `export fn timesFive(x) {
+const FEATURE_TREE_EXAMPLE_CODE = `export fn timesFive(@x) {
   return 5 * x
 }
 export fn triangle() {