api!: remove verification methods from the FFI and JSON-RPC APIs

Core no longer tracks verification, so the API has nothing left
to report and UIs should drop their checkmark and "Introduced by" code.

BREAKING CHANGE: dc_contact_is_verified() and dc_contact_get_verifier_id() are removed.

BREAKING CHANGE: the JSON-RPC Contact object loses the `isVerified` and `verifierId` fields. A bot reading `snapshot.is_verified` now gets an `AttributeError` at runtime.

BREAKING CHANGE: the Python bindings lose `Contact.is_verified()` and `Contact.get_verifier()`.

BREAKING CHANGE: DC_STR_CONTACT_VERIFIED (35) is removed, so UIs should stop registering a translation for it. A stock id core does not know is logged and otherwise ignored, so an un-updated client keeps working.

deltachat-repl/src/cmdline.rs

@@ -259,19 +259,13 @@ async fn log_contactlist(context: &Context, contacts: &[ContactId]) -> Result<()
         let contact = Contact::get_by_id(context, *contact_id).await?;
         let name = contact.get_display_name();
         let addr = contact.get_addr();
-        let verified_str = if contact.is_verified(context).await? {
-            " √"
-        } else {
-            ""
-        };
         let line = format!(
-            "{}{} <{}>",
+            "{} <{}>",
             if !name.is_empty() {
                 name
             } else {
                 "<name unset>"
             },
-            verified_str,
             if !addr.is_empty() { addr } else { "addr unset" }
         );