feat: attach Substrait version number to plans

proto/substrait/plan.proto

@@ -24,6 +24,10 @@ message PlanRel {
 // Describe a set of operations to complete.
 // For compactness sake, identifiers are normalized at the plan level.
 message Plan {
+  // Substrait version of the plan. Optional up to 0.16.0, required for later
+  // versions.
+  Version version = 6;
+
   // a list of yaml specifications this plan may depend on
   repeated substrait.extensions.SimpleExtensionURI extension_uris = 1;
 
@@ -43,3 +47,20 @@ message Plan {
   // one or more message types defined here are unknown.
   repeated string expected_type_urls = 5;
 }
+
+message Version {
+  // Substrait version number.
+  uint32 major = 1;
+  uint32 minor = 2;
+  uint32 patch = 3;
+
+  // If a particular version of Substrait is used that does not correspond to
+  // a version number exactly (for example when using an unofficial fork or
+  // using a version that is not yet released or is between versions), set this
+  // to the full git hash of the utilized commit of
+  // https://github.com/substrait-io/substrait (or fork thereof), represented
+  // using a lowercase hex ASCII string 40 characters in length. The version
+  // number above should be set to the most recent version tag in the history
+  // of that commit.
+  string git_hash = 4;
+}