patch 8.2.3830: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/evalvars.c b/src/evalvars.c
index 6aa2e42..1a50db0 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -1858,7 +1858,7 @@
     }
     if (forceit)
 	return OK;
-    semsg(_("E108: No such variable: \"%s\""), name);
+    semsg(_(e_no_such_variable_str), name);
     return FAIL;
 }