feat(history): Remove group history on quit when selected

The group itself is a peer, as well as all the members of the group.
Members of the group have associated aliases, but the group does not.
Chat messages reference the chat_id of the group, with senders
referencing the member peer.

Deleting all history belonging to the chat_id already generically cleans
up group history. Users who only have history from that group need to
have their aliases and peer entries removed.

We don't store what users or aliases were in which group, so just remove
any alias that has no associated chat message with it, and peer that
doesn't have an alias (friend with history) and doesn't have a chat
message associated with it as a chat_id (group).

The group itself is removed from the peer table directly, and the group
never has an alias entry.

src/persistence/history.cpp

@@ -271,8 +271,15 @@ void History::removeChatHistory(const ChatId& chatId)
                                 "   SELECT id from history "
                                 "   WHERE message_type = 'S' AND chat_id=%1);"
                                 "DELETE FROM history WHERE chat_id=%1; "
-                                "DELETE FROM aliases WHERE owner=%1; "
-                                "DELETE FROM peers WHERE id=%1; "
+                                "DELETE FROM aliases "
+                                "WHERE id NOT IN ( "
+                                "    SELECT DISTINCT sender_alias FROM text_messages);"
+                                "DELETE FROM peers "
+                                "WHERE id NOT IN ( "
+                                "    SELECT DISTINCT chat_id FROM history "
+                                "    UNION SELECT DISTINCT owner from aliases); "
+                                "DELETE FROM aliases WHERE owner=%1;"
+                                "DELETE FROM peers WHERE id=%1;"
                                 "VACUUM;")
                             .arg(generatePeerIdString(chatId));