chore: Simplify extension dependency injection

- Has better typing
- Removes use of unnusual unique symbol
- Fix welcome banner tests
    - Update associated snapshots
- Start converting custom column tests to use ApplicationBuilder
- Remove old and unnused RecursiveTreeView
- Introduce new TreeView for use in CatalogMenu to fix tests

Signed-off-by: Sebastian Malton <sebastian@malton.name>

packages/technical-features/application/legacy-extensions/src/bundled-extension.ts

@@ -4,10 +4,12 @@ import type {
   BundledLensExtensionManifest,
 } from "./lens-extension";
 
+export type BundledExtensionResult = BundledLensExtensionConstructor | null;
+
 export interface BundledExtension {
   readonly manifest: BundledLensExtensionManifest;
-  main: () => Promise<BundledLensExtensionConstructor | null>;
-  renderer: () => Promise<BundledLensExtensionConstructor | null>;
+  main: () => BundledExtensionResult | Promise<BundledExtensionResult>;
+  renderer: () => BundledExtensionResult | Promise<BundledExtensionResult>;
 }
 
 export const bundledExtensionInjectionToken =