Do not add messages into `smtp` queue if the only recipient is self and `bcc_self` is off or deletion is set to immediate

[link2xt]

Since change
#5190
even if delete_server_after is immediate, we send a message to self when bcc_self is enabled. However, we should not send any messages over SMTP if delete_server_after is immediate and the only recipient is self, e.g. in Saved messages chat or in a group with only self.

Current code is here:

core/src/chat.rs

Lines 3020 to 3038 in 82f6103

	// Send BCC to self if it is enabled.
	//
	// Previous versions of Delta Chat did not send BCC self
	// if DeleteServerAfter was set to immediately delete messages
	// from the server. This is not the case anymore
	// because BCC-self messages are also used to detect
	// that message was sent if SMTP server is slow to respond
	// and connection is frequently lost
	// before receiving status line. NB: This is not a problem for chatmail servers, so `BccSelf`
	// disabled by default is fine.
	//
	// `from` must be the last addr, see `receive_imf_inner()` why.
	if context.get_config_bool(Config::BccSelf).await?
	&& !recipients
	.iter()
	.any(|x| x.to_lowercase() == lowercase_from)
	{
	recipients.push(from);
	}