refactor: Move logins into SQL table (#6724)

Move all `configured_*` parameters into a new SQL table `transports`.
All `configured_*` parameters are deprecated; the only exception is
`configured_addr`, which is used to store the address of the primary
transport. Currently, there can only ever be one primary transport (i.e.
the `transports` table only ever has one row); this PR is not supposed
to change DC's behavior in any meaningful way.

This is a preparation for mt.

---------

Co-authored-by: l <link2xt@testrun.org>

src/receive_imf/receive_imf_tests.rs

@@ -3113,7 +3113,6 @@ Message with references."#;
 async fn test_rfc1847_encapsulation() -> Result<()> {
     let alice = TestContext::new_alice().await;
     let bob = TestContext::new_bob().await;
-    alice.configure_addr("alice@example.org").await;
 
     // Alice sends an Autocrypt message to Bob so Bob gets Alice's key.
     let chat_alice = alice.create_chat(&bob).await;