feat: Case-insensitive search for non-ASCII chat and contact names (#7477)

This makes `Contact::get_all()` and `Chatlist::try_load()` case-insensitive for non-ASCII chat and
contact names as well. The same approach as in f6f4ccc6ea "feat:
Case-insensitive search for non-ASCII messages (#5052)" is used: `chats.name_normalized` and
`contacts.name_normalized` colums are added which store lowercased/normalized names (for a contact,
if the name is unset, it's a normalized authname). If a normalized name is the same as the
chat/contact name, it's not stored to reduce the db size. A db migration is added for 10000 random
chats and the same number of the most recently seen contacts, for users it will probably migrate all
chats/contacts and for bots which may have more data it's not important.

src/message.rs

@@ -2248,14 +2248,5 @@ impl Viewtype {
     }
 }
 
-/// Returns text for storing in the `msgs.txt_normalized` column (to make case-insensitive search
-/// possible for non-ASCII messages).
-pub(crate) fn normalize_text(text: &str) -> Option<String> {
-    if text.is_ascii() {
-        return None;
-    };
-    Some(text.to_lowercase()).filter(|t| t != text)
-}
-
 #[cfg(test)]
 mod message_tests;