Remove useUniversalComponents and the native Basic Catalog from the Angular renderer #4148

Tracking issue for removing RendererConfiguration.useUniversalComponents and the native Angular Basic Catalog from @a2ui/angular.

With the flag on, Basic Catalog components render as the universal web components from @a2ui/web_core, and custom Angular components are wrapped in custom elements so universal containers can render them. Once every consumer runs with the flag on, the flag and the native Angular copy of the Basic Catalog become dead code.

Prerequisites

Fixes that apps with several renderers need before they can turn the flag on:

• fix(angular): resolve universal element injectors per renderer #4129 Plain AngularCatalog entries render inside universal containers, each renderer instance resolves its own injector, and subclassed elements get their own scoped styles.
• feat(angular): add onElementConnected hook for universal elements #4143 onElementConnected hook, so hosts can decorate universal elements they don't own (for example, analytics attributes) without subclassing them.
• Google-internal consumers migrated to useUniversalComponents: true.

Removal

• Default useUniversalComponents to true in provideA2Ui (the v1.0 provideA2UI already does).
• Delete the flag from RendererConfiguration and A2uiRendererService, and make ComponentHostComponent always mount the Web Component when an entry has one.
• Delete the native Basic Catalog components in typescript/renderers/angular/src/v0_9/catalog/basic/*.component.ts and basic-catalog-component.ts. BASIC_COMPONENTS and BasicCatalog then use the @a2ui/web_core elements directly.
• Delete UniversalOnlyComponent and the placeholder workaround in toAngularComponentImplementation.
• Update the Angular explorer, samples, docs, and CHANGELOG (breaking change).