feat: add "e2ee encrypted" info message to all e2ee chats (#7008)

this PR adds a info message "messages are end-to-end-encrypted" also for
chats created by eg. vcards. by the removal of lock icons, this is a
good place to hint for that in addition; this is also what eg. whatsapp
and others are doing

the wording itself is tweaked at
https://github.com/deltachat/deltachat-android/pull/3817 (and there is
also the rough idea to make the message a little more outstanding, by
some more dedicated colors)

~~did not test in practise, if this leads to double "e2ee info messages"
on secure join, tests look good, however.~~ EDIT: did lots of practise
tests meanwhile :)

most of the changes in this PR are about test ...

ftr, in another PR, after 2.0 reeases, there could probably quite some
code cleanup wrt set-protection, protection-disabled etc.

---------

Co-authored-by: Hocuri <hocuri@gmx.de>

src/download.rs

@@ -277,7 +277,7 @@ mod tests {
     use crate::chat::{get_chat_msgs, send_msg};
     use crate::ephemeral::Timer;
     use crate::receive_imf::receive_imf_from_inbox;
-    use crate::test_utils::TestContext;
+    use crate::test_utils::{E2EE_INFO_MSGS, TestContext};
 
     #[test]
     fn test_downloadstate_values() {
@@ -459,7 +459,10 @@ mod tests {
         .await?;
         let msg = bob.get_last_msg().await;
         let chat_id = msg.chat_id;
-        assert_eq!(get_chat_msgs(&bob, chat_id).await?.len(), 1);
+        assert_eq!(
+            get_chat_msgs(&bob, chat_id).await?.len(),
+            E2EE_INFO_MSGS + 1
+        );
         assert_eq!(msg.download_state(), DownloadState::Available);
 
         // downloading the status update afterwards expands to nothing and moves the placeholder to trash-chat
@@ -472,7 +475,7 @@ mod tests {
             None,
         )
         .await?;
-        assert_eq!(get_chat_msgs(&bob, chat_id).await?.len(), 0);
+        assert_eq!(get_chat_msgs(&bob, chat_id).await?.len(), E2EE_INFO_MSGS);
         assert!(
             Message::load_from_db_optional(&bob, msg.id)
                 .await?