fix: going back to using auth headers for SupabaseQueryBuilder

[dshukertjr]

What kind of change does this PR introduce?

Currently, when user performs an query right after signing in, the query is performed with the session prior to signing in, resulting in empty query result. This PR fixes that.

await client.auth.signInWithPassword(email: email, password: password);

/// Unable to retrieve data if the data is protected with RLS
final data = await client
    .from('profiles')
    .select()
    .eq('user_id', response.user?.id);

Fixes supabase/supabase-flutter#456

[bdlukaa]

Can't we have both auth and other headers?

[Vinzent03]

The problem itself though persists with storage and functions client. I think a possibility is making the onAuthStateChanged stream sync, so that the listener is instantly called. I think that would be fine with our own listener, but I don't know the consequences for the listeners in the users application. Maybe we add two streams? One async and one sync?

[dshukertjr]

@Vinzent03
Although the problem persists with storage and functions client, the postgrest client is by far the most commonly used right after sining in. Let's ship a fix for this particular use case and discuss how to properly handle it for storage and functions client.