Switch from Vec<InlayKind> to object with props

- Instead of a single object type, use several individual nested types
  to allow toggling from the settings GUI
- Remove unused struct definitions
- Install and test that the toggles work

editors/code/src/inlay_hints.ts

@@ -10,7 +10,7 @@ export function activateInlayHints(ctx: Ctx) {
     const maybeUpdater = {
         updater: null as null | HintsUpdater,
         onConfigChange() {
-            if (ctx.config.inlayHintOpts.displayType === 'off') {
+            if (!ctx.config.inlayHints.typeHints && !ctx.config.inlayHints.parameterHints) {
                 return this.dispose();
             }
             if (!this.updater) this.updater = new HintsUpdater(ctx);