Just a tiny nit i came across - realised that if the schema is not
exposed via the API, the warning that we show on the policies page RE
data not being selectable is repeated for each table which imo seems
unnecessary.
Opting for a single admonition at the top instead
## Before
<img width="1085" height="744" alt="image"
src="https://github.com/user-attachments/assets/7bd8cf7b-f5a8-47d6-b41f-13fc4782ed8b"
/>
### After
<img width="1080" height="673" alt="image"
src="https://github.com/user-attachments/assets/c839f502-42ff-4184-ad07-0ff2fd2d2676"
/>
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added an on-screen warning for tables whose schemas aren’t exposed via
the project Data APIs, including a link to Data API settings.
* **UI Improvements**
* Refined the “filter entity types” control’s tooltip behavior and
updated the popover header text.
* **Bug Fixes**
* Improved Data API/RLS status messaging by removing the prior “schema
not exposed” outcome and showing “unknown” when access can’t be
determined.
* Consolidated policy warning rendering to avoid duplicated or
inconsistent messages.
* **Tests**
* Updated policy/admonition helper tests to match the revised status and
message behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
## Context
Previous PR was [here](https://github.com/supabase/supabase/pull/45143)
but it got stale with lots of conflicts so figured it'll be easier redo
it off the latest master
Moves policies page from Auth to Database under an Access Control
section along with Roles. This moves all existing files, applies
redirects, and updates urls to point to the new route
<img width="274" height="412" alt="image"
src="https://github.com/user-attachments/assets/7952c185-64ae-4355-ba36-45397efe1787"
/>
<img width="453" height="471" alt="image"
src="https://github.com/user-attachments/assets/04b3dcb3-48a5-4049-9893-d01109fb46a9"
/>
## To test
- [ ] Verify that policies now live under Database correctly
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added a quick navigation shortcut to open **Database > Policies
(RLS)**.
* **Bug Fixes**
* Updated Policies and RLS-related links across the product to open the
**Database policies** area (menus, command palette, context actions,
alerts, and link-outs).
* Added a permanent redirect from the old **auth policies** URL to the
new **database policies** URL.
* **Documentation**
* Updated RLS Dashboard and security checklist instructions to reference
**Database > Policies**.
* **Tests**
* Adjusted automated tests to validate the new Policies route.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
