Example code update with CustomSupabaseSessionHandler and new page example with RLS

[rhuanbarros]

What kind of change does this PR introduce?

New feature.
Example code updated with CustomSupabaseSessionHandler and new page example with RLS

What is the current behavior?

The session is not saved to local storage.
There is no page example of working with table with policies.

What is the new behavior?

The session is saved to local storage.
There is a page example of working with table with policies.

Additional context

There is a bug with the SessionRetriever in the CustomSupabaseSessionHandler that I could not fix. Hopefuly I could fix later or could get some help.

[acupofjose]

@rhuanbarros thanks for this! I think it's running into a race condition where supabase.InitializeAsync() is being called in multiple places and not completed before the page is rendered. I moved that into your custom auth handler instead and it seemed to be working for me!

Care to try it out?

[rhuanbarros]

@acupofjose I just tested and it's working fine! I get what you did. Thank you
This helped me a lot
😄