patch 8.2.3069: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move some error messages to errors.h.  Use clearer names.
diff --git a/src/arglist.c b/src/arglist.c
index 79628fd..863b1cc 100644
--- a/src/arglist.c
+++ b/src/arglist.c
@@ -832,7 +832,7 @@
 	{
 	    // Don't give an error for ":%argdel" if the list is empty.
 	    if (eap->line1 != 1 || eap->line2 != 0)
-		emsg(_(e_invrange));
+		emsg(_(e_invalid_range));
 	}
 	else
 	{
@@ -920,7 +920,7 @@
 #ifdef FEAT_CMDWIN
     if (cmdwin_type != 0)
     {
-	emsg(_(e_cmdwin));
+	emsg(_(e_invalid_in_cmdline_window));
 	return;
     }
 #endif