build(docs-infra): remove obsolete `typings.d.ts` files from angular.io and docs examples (#38173)

There were two `typings.d.ts` files with SystemJS module definitions in
`aio/src/` and `aio/tools/examples/shared/boilerplate/cli/`. These are
remnants from old CLI versions that used SystemJS and are no longer
needed. For docs examples specifically, these files were never copied
over to example projects and thus not included in StackBlitz projects
and ZIP archives.

This commit removes these obsolete files.

PR Close #38173

aio/src/typings.d.ts

@@ -1,5 +0,0 @@
-/* SystemJS module definition */
-declare var module: NodeModule;
-interface NodeModule {
-  id: string;
-}

aio/tools/example-zipper/exampleZipper.js

@@ -98,7 +98,6 @@ class ExampleZipper {
       'src/favicon.ico',
       'src/polyfills.ts',
       'src/test.ts',
-      'src/typings.d.ts',
       'src/environments/**/*',
       'src/testing/**/*',
       // Only ignore root package.json

aio/tools/examples/shared/boilerplate/cli/src/typings.d.ts

@@ -1,5 +0,0 @@
-/* SystemJS module definition */
-declare var module: NodeModule;
-interface NodeModule {
-  id: string;
-}