Move TFDV stats to higher-numbered protobuf fields (#669)

Within the Feast v0.5 release cycle these fields have not been in a
release yet, so it's safe to renumber them.

The motivation is reserving the lower-numbered fields for optimal
encoding, referenced in the patch.

Closes #667

protos/feast/core/FeatureSet.proto

@@ -120,48 +120,55 @@ message FeatureSpec {
     // Value type of the feature.
     feast.types.ValueType.Enum value_type = 2;
 
+    // Reserve field numbers 15 and below for fields that will almost always be set
+    // https://developers.google.com/protocol-buffers/docs/proto3#assigning-field-numbers
+    reserved 3 to 15;
+
+    // Labels for user defined metadata on a feature
+    map<string,string> labels = 16;
+
+    // Reserved for fundamental future additions less noisy in the schema that TFDV stats fields
+    reserved 17 to 29;
+
     // presence_constraints, shape_type and domain_info are referenced from:
     // https://github.com/tensorflow/metadata/blob/36f65d1268cbc92cdbcf812ee03dcf47fb53b91e/tensorflow_metadata/proto/v0/schema.proto#L107
 
     oneof presence_constraints {
         // Constraints on the presence of this feature in the examples.
-        tensorflow.metadata.v0.FeaturePresence presence = 3;
+        tensorflow.metadata.v0.FeaturePresence presence = 30;
         // Only used in the context of a "group" context, e.g., inside a sequence.
-        tensorflow.metadata.v0.FeaturePresenceWithinGroup group_presence = 4;
+        tensorflow.metadata.v0.FeaturePresenceWithinGroup group_presence = 31;
     }
 
     // The shape of the feature which governs the number of values that appear in
     // each example.
     oneof shape_type {
         // The feature has a fixed shape corresponding to a multi-dimensional
         // tensor.
-        tensorflow.metadata.v0.FixedShape shape = 5;
+        tensorflow.metadata.v0.FixedShape shape = 32;
         // The feature doesn't have a well defined shape. All we know are limits on
         // the minimum and maximum number of values.
-        tensorflow.metadata.v0.ValueCount value_count = 6;
+        tensorflow.metadata.v0.ValueCount value_count = 33;
     }
 
     // Domain for the values of the feature.
     oneof domain_info {
         // Reference to a domain defined at the schema level.
-        string domain = 7;
+        string domain = 34;
         // Inline definitions of domains.
-        tensorflow.metadata.v0.IntDomain int_domain = 8;
-        tensorflow.metadata.v0.FloatDomain float_domain = 9;
-        tensorflow.metadata.v0.StringDomain string_domain = 10;
-        tensorflow.metadata.v0.BoolDomain bool_domain = 11;
-        tensorflow.metadata.v0.StructDomain struct_domain = 12;
+        tensorflow.metadata.v0.IntDomain int_domain = 35;
+        tensorflow.metadata.v0.FloatDomain float_domain = 36;
+        tensorflow.metadata.v0.StringDomain string_domain = 37;
+        tensorflow.metadata.v0.BoolDomain bool_domain = 38;
+        tensorflow.metadata.v0.StructDomain struct_domain = 39;
         // Supported semantic domains.
-        tensorflow.metadata.v0.NaturalLanguageDomain natural_language_domain = 13;
-        tensorflow.metadata.v0.ImageDomain image_domain = 14;
-        tensorflow.metadata.v0.MIDDomain mid_domain = 15;
-        tensorflow.metadata.v0.URLDomain url_domain = 16;
-        tensorflow.metadata.v0.TimeDomain time_domain = 17;
-        tensorflow.metadata.v0.TimeOfDayDomain time_of_day_domain = 18;
+        tensorflow.metadata.v0.NaturalLanguageDomain natural_language_domain = 40;
+        tensorflow.metadata.v0.ImageDomain image_domain = 41;
+        tensorflow.metadata.v0.MIDDomain mid_domain = 42;
+        tensorflow.metadata.v0.URLDomain url_domain = 43;
+        tensorflow.metadata.v0.TimeDomain time_domain = 44;
+        tensorflow.metadata.v0.TimeOfDayDomain time_of_day_domain = 45;
     }
-
-    // Labels for user defined metadata on a feature
-    map<string,string> labels = 19;
 }
 
 message FeatureSetMeta {