Add Pagehead stories (#3042)

* Add `Pagehead` story

* Update docs path

* Add Playground

* Enable test

* Update generated/components.json

* Add e2e test

* test(vrt): update snapshots

* Re-run `generate-e2e-tests`

---------

Co-authored-by: simurai <[email protected]>

Author: simurai

.playwright/snapshots/components/Pagehead.test.ts-snapshots/Pagehead-Default-dark-colorblind-linux.png

@@ -6,7 +6,7 @@ source: https://github.com/primer/react/blob/main/src/Pagehead.tsx
 status: Alpha
 ---
 
-import data from '../../src/Pagehead.docs.json'
+import data from '../../src/Pagehead/Pagehead.docs.json'
 
 ```js
 import {Pagehead} from '@primer/react'