renaming thrift names

Author: ezvz

api/thrift/api.thrift

@@ -258,7 +258,9 @@ struct MetaData {
     // column -> tag_key -> tag_value
     7: optional map<string, map<string, string>> columnTags
 
-    8: optional list<lineage.StageColumnLineage> stageColumnLineages
+    // A stage is a "sub-transformation" of a given node. For example a `GroupBy` can consist of selects (with SQL expressions), filters (in the form of where clauses), followed by aggregations defined in the Zipline DSL.
+    // Each of this is a `stage` with its own column level lineage.
+    8: optional list<lineage.StageWithLineage> stagesWithLineage
 
     // marking this as true means that the conf can be served online
     // once marked online, a conf cannot be changed - compiling the conf won't be allowed

api/thrift/lineage.thrift

@@ -48,7 +48,7 @@ struct ColumnLineage {
     4: optional ColumnLineageType lineageType // not present means direct
 }
 
-struct StageColumnLineage {
+struct StageWithLineage {
     1: optional ColumnLineageStage stage
     2: optional list<ColumnLineage> lineage
 }