patch 8.2.3985: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/message.c b/src/message.c
index a930a80..81c0f47 100644
--- a/src/message.c
+++ b/src/message.c
@@ -891,7 +891,7 @@
     void
 emsg_invreg(int name)
 {
-    semsg(_("E354: Invalid register name: '%s'"), transchar(name));
+    semsg(_(e_invalid_register_name_str), transchar(name));
 }
 
 /*