move ASM strings to core, point to "Add Second Device" (#6777)

this PR moves now advanced/unsupported ASM strings to core, removing
work from translations, esp. as another hint is added which would
require retranslations. it is better to have that just in english, it is
a nerd feature anyways.

moverover, this PR removes special rendering of ASM in the summary,
which might be confusion, but mainly it is now unneeded, dead code

i'll do another android PR that will point to "Add Second Device"
already on ASM generation EDIT: done at
https://github.com/deltachat/deltachat-android/pull/3726

targets https://github.com/deltachat/deltachat-desktop/issues/4946

src/constants.rs

@@ -220,6 +220,19 @@ pub(crate) const SECUREJOIN_WAIT_TIMEOUT: u64 = 15;
 // Newer Delta Chats will remove the prefix as needed.
 pub(crate) const EDITED_PREFIX: &str = "✏️";
 
+// Strings needed to render the Autocrypt Setup Message.
+// Left untranslated as not being supported/recommended workflow and as translations would require deep knowledge.
+pub(crate) const ASM_SUBJECT: &str = "Autocrypt Setup Message";
+pub(crate) const ASM_BODY: &str = "This is the Autocrypt Setup Message \
+    used to transfer your end-to-end setup between clients.
+
+    To decrypt and use your setup, \
+    open the message in an Autocrypt-compliant client \
+    and enter the setup code presented on the generating device.
+
+    If you see this message in a chatmail client (Delta Chat, Arcane Chat, Delta Touch ...), \
+    use \"Settings / Add Second Device\" instead.";
+
 #[cfg(test)]
 mod tests {
     use num_traits::FromPrimitive;