patch 8.2.4010: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/crypt.c b/src/crypt.c
index f2f643f..5a83588 100644
--- a/src/crypt.c
+++ b/src/crypt.c
@@ -200,7 +200,7 @@
 
     i = (int)STRLEN(crypt_magic_head);
     if (len >= i && memcmp(ptr, crypt_magic_head, i) == 0)
-	emsg(_("E821: File is encrypted with unknown method"));
+	emsg(_(e_file_is_encrypted_with_unknown_method));
 
     return -1;
 }