Move module functions to type methods

This moves the module-level lookup and creation functions to the
types, which make the naming more consistent.  Now the lookup_* get_*
and create_* functions all behave similarly.

Peraps even more important the API of the lookup now allows
distinguishing failure from not found.  This in turn is important to
be able to remove reliance on a ChatId with a 0 or "unset" value.  The
locations where this ChatId(0) is still used is in database queries
which should be solved in an independed commit.

src/chatlist.rs

@@ -2,7 +2,6 @@
 
 use anyhow::{bail, ensure, Result};
 
-use crate::chat;
 use crate::chat::{update_special_chat_names, Chat, ChatId, ChatVisibility};
 use crate::constants::{
     Chattype, DC_CHAT_ID_ALLDONE_HINT, DC_CHAT_ID_ARCHIVED_LINK, DC_CHAT_ID_DEADDROP,
@@ -110,15 +109,6 @@ impl Chatlist {
 
         let mut add_archived_link_item = false;
 
-        let skip_id = if flag_for_forwarding {
-            chat::lookup_by_contact_id(context, DC_CONTACT_ID_DEVICE)
-                .await
-                .unwrap_or_default()
-                .0
-        } else {
-            ChatId::new(0)
-        };
-
         let process_row = |row: &rusqlite::Row| {
             let chat_id: ChatId = row.get(0)?;
             let msg_id: MsgId = row.get(1).unwrap_or_default();
@@ -130,6 +120,14 @@ impl Chatlist {
                 .map_err(Into::into)
         };
 
+        let skip_id = if flag_for_forwarding {
+            ChatId::lookup_by_contact(context, DC_CONTACT_ID_DEVICE)
+                .await?
+                .unwrap_or_default()
+        } else {
+            ChatId::new(0)
+        };
+
         // select with left join and minimum:
         //
         // - the inner select must use `hidden` and _not_ `m.hidden`
@@ -232,10 +230,9 @@ impl Chatlist {
         } else {
             //  show normal chatlist
             let sort_id_up = if flag_for_forwarding {
-                chat::lookup_by_contact_id(context, DC_CONTACT_ID_SELF)
-                    .await
+                ChatId::lookup_by_contact(context, DC_CONTACT_ID_SELF)
+                    .await?
                     .unwrap_or_default()
-                    .0
             } else {
                 ChatId::new(0)
             };