* ui: Change action-group to use new popup-menu component in intentions
* ui: Slight amends to aria-menu to prevent scrolling
* ui: Begin to use aria-menu/popover-menu for other elements
* Use a simpler, hackier method to fix up zIndexing
* ui: Implement new confirmation dialogs in other list views (#7080)
This includes another amend to the popover-menu in order to allow
mutiple confirmations/subpanels in the same popover menu.
The functionality added here to allow this is likely to change in the
future.
Adds namespace support to the UI:
1. Namespace CRUD/management
2. Show Namespace in relevant areas (intentions, upstreams)
3. Main navigation bar improvements
4. Logic/integration to interact with a new `internal/acl/authorize` endpoint
