patch 8.2.3967: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more errors to errors.h.
diff --git a/src/dict.c b/src/dict.c
index 6773c75..0c9cea3 100644
--- a/src/dict.c
+++ b/src/dict.c
@@ -1414,7 +1414,7 @@
     di = dict_find(d, key, -1);
     if (di == NULL)
     {
-	semsg(_(e_dictkey), key);
+	semsg(_(e_key_not_present_in_dictionary), key);
 	return;
     }
 
@@ -1449,7 +1449,7 @@
 
     if (argvars[0].v_type != VAR_DICT)
     {
-	emsg(_(e_dictreq));
+	emsg(_(e_dictionary_required));
 	return;
     }
 
@@ -1572,7 +1572,7 @@
 
     if (argvars[0].v_type != VAR_DICT)
     {
-	emsg(_(e_dictreq));
+	emsg(_(e_dictionary_required));
 	return;
     }
     if (argvars[0].vval.v_dict == NULL)