Add CommitCheckStatus filter to ListLabelHistory (#80)

This is helpful so the review flow UI can fetch only commits that are
pending on a label.

buf/registry/module/v1/label_service.proto

@@ -156,6 +156,10 @@ message ListLabelHistoryRequest {
   // TODO: We are purposefully not making the default the zero enum value, however
   // we may want to consider this.
   Order order = 4 [(buf.validate.field).enum.defined_only = true];
+  // Only return Commits that have one of these CommitCheckStatus values for this label.
+  //
+  // If not set, Commits with any CommitCheckStatus value are returned.
+  repeated CommitCheckStatus commit_check_statuses = 6 [(buf.validate.field).repeated.items.enum.defined_only = true];
 }
 
 message ListLabelHistoryResponse {

buf/registry/module/v1beta1/label_service.proto

@@ -164,6 +164,10 @@ message ListLabelHistoryRequest {
   //
   // If not set, the latest DigestType is used, currently B5.
   DigestType digest_type = 5 [(buf.validate.field).enum.defined_only = true];
+  // Only return Commits that have one of these CommitCheckStatus values for this label.
+  //
+  // If not set, Commits with any CommitCheckStatus value are returned.
+  repeated CommitCheckStatus commit_check_statuses = 6 [(buf.validate.field).repeated.items.enum.defined_only = true];
 }
 
 message ListLabelHistoryResponse {