feat(frontend): Add option for plugins to add header actions (#9570)

* [FR] PUI - Add option for plugins to add header actions
Fixes #8593

* fix parsing

* fix merge

* reduce diff

* fix sample implementation

* add support for icons and colors in primary actions

* add changelog entry

* add docs

* add more detailed sample text

* pass location into context

* fix test

---------

Co-authored-by: Oliver <oliver.henry.walters@gmail.com>

src/frontend/tests/pages/pui_stock.spec.ts

@@ -100,11 +100,8 @@ test('Stock - Location Delete', async ({ browser }) => {
 
   // Delete this location, and all child locations
   await page
-    .locator('div')
-    .filter({
-      hasText: new RegExp(`^Stock>PCB Assembler>${loc_1}Stock Location$`)
-    })
-    .getByLabel('action-menu-location-actions')
+    .getByRole('button', { name: 'action-menu-location-actions' })
+    .first()
     .click();
   await page
     .getByRole('menuitem', { name: 'action-menu-location-actions-delete' })