build: remove a11y-demo (#18551)

The accessibility demo pages aren't used anymore and aren't exposed anywhere. These changes get rid of all of the code.

Author: crisbeto

.github/CODEOWNERS

@@ -128,9 +128,6 @@
 /guides/**                                         @jelbourn
 /src/components-examples/**                        @jelbourn
 
-# Accessibility demos
-/src/a11y-demo/**/*                                @jelbourn
-
 # Dev-app
 /src/dev-app/*                                     @jelbourn
 /src/dev-app/autocomplete/**                       @crisbeto

scripts/check-rollup-globals.ts

@@ -27,7 +27,7 @@ const configFile = ts.readJsonConfigFile(join(projectRoot, 'tsconfig.json'), ts.
 const parsedConfig = ts.parseJsonSourceFileConfigFileContent(configFile, ts.sys, projectRoot);
 const filesToCheckGlob = [
   'src/**/!(*.spec).ts',
-  '!src/+(a11y-demo|e2e-app|universal-app|dev-app)/**/*.ts',
+  '!src/+(e2e-app|universal-app|dev-app)/**/*.ts',
   '!src/**/schematics/**/*.ts',
 ];