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/strings.c b/src/strings.c
index 496312d..5c55c1e 100644
--- a/src/strings.c
+++ b/src/strings.c
@@ -1934,7 +1934,7 @@
 	else if (tvs[idx].v_type == VAR_NUMBER)
 	    f = (double)tvs[idx].vval.v_number;
 	else
-	    emsg(_("E807: Expected Float argument for printf()"));
+	    emsg(_(e_expected_float_argument_for_printf));
     }
     return f;
 }