feat: use dedicated 'call' viewtype (#7174)

a dedicated viewtype allows the UI to show a more advanced UI, but even
when using the defaults,
it has the advantage that incoming/outgoing and the date are directly
visible.

successor of https://github.com/chatmail/core/pull/6650

src/message.rs

@@ -973,8 +973,6 @@ impl Message {
             | SystemMessage::WebxdcStatusUpdate
             | SystemMessage::WebxdcInfoMessage
             | SystemMessage::IrohNodeAddr
-            | SystemMessage::OutgoingCall
-            | SystemMessage::IncomingCall
             | SystemMessage::CallAccepted
             | SystemMessage::CallEnded
             | SystemMessage::Unknown => Ok(None),
@@ -2280,6 +2278,9 @@ pub enum Viewtype {
     /// Message is an invitation to a videochat.
     VideochatInvitation = 70,
 
+    /// Message is an incoming or outgoing call.
+    Call = 71,
+
     /// Message is an webxdc instance.
     Webxdc = 80,
 
@@ -2303,6 +2304,7 @@ impl Viewtype {
             Viewtype::Video => true,
             Viewtype::File => true,
             Viewtype::VideochatInvitation => false,
+            Viewtype::Call => false,
             Viewtype::Webxdc => true,
             Viewtype::Vcard => true,
         }