core: show group as sender, add contact card to contact request chats, unify api type for prepared and contact request chats (#6003)

* core: option to show group as sender of chat item (for the initial items, e.g. welcome message)

* add chat item to contact request chats

* return AChat for prepared chats and contact requests

* update iOS api types, show prepared contact as blue, show preview info when content message is not available (previously was showing feature item)

* ios: remove ContactType

* ios: show group as sender, fix avatar not showing when member message sequence starts with merged items

* ios: update compose UI for all connection scenarios

* address settings

* ios: address settings UI

* fix tests

* fix tests 2

* ios: fix minor issues

src/Simplex/Chat/Store/SQLite/Migrations/chat_schema.sql

@@ -333,6 +333,7 @@ CREATE TABLE user_contact_links(
   business_address INTEGER DEFAULT 0,
   short_link_contact BLOB,
   short_link_data_set INTEGER NOT NULL DEFAULT 0,
+  address_welcome_message TEXT,
   UNIQUE(user_id, local_display_name)
 );
 CREATE TABLE contact_requests(
@@ -426,7 +427,8 @@ CREATE TABLE chat_items(
   include_in_history INTEGER NOT NULL DEFAULT 0,
   user_mention INTEGER NOT NULL DEFAULT 0,
   group_scope_tag TEXT,
-  group_scope_group_member_id INTEGER REFERENCES group_members(group_member_id) ON DELETE CASCADE
+  group_scope_group_member_id INTEGER REFERENCES group_members(group_member_id) ON DELETE CASCADE,
+  show_group_as_sender INTEGER NOT NULL DEFAULT 0
 );
 CREATE TABLE sqlite_sequence(name,seq);
 CREATE TABLE chat_item_messages(