Other: Do not decode message body during send record hashing

When calculating the hash for the body to match against sent email to
avoid duplicate addition to the sent folder, do not decode the actual
contents of the body.

It is possible that certain attachments are not formed correctly but
can still accepted by the backend. Trimming spaces and \r characters is
enough to hash the message and match it later on.

This also speeds the process up as we no longer have to perform
encoding conversions.

internal/user/send_recorder.go

@@ -275,12 +275,10 @@ func getMessageHash(b []byte) (string, error) {
 			return err
 		}
 
-		body, err := section.DecodedBody()
-		if err != nil {
-			return err
-		}
-
-		if _, err := h.Write(bytes.TrimSpace(body)); err != nil {
+		body := section.Body()
+		body = bytes.ReplaceAll(body, []byte{'\r'}, nil)
+		body = bytes.TrimSpace(body)
+		if _, err := h.Write(body); err != nil {
 			return err
 		}