Sub-issue of #22418. Port ScalarSubqueryExpr to use the try_to_proto / try_from_proto hooks added in #21929.
Replace the ScalarSubqueryExpr arm in datafusion/proto/src/physical_plan/{to_proto,from_proto}.rs with try_to_proto / try_from_proto impls next to ScalarSubqueryExpr. See the Column / BinaryExpr migrations in #21929 for reference.
Sub-issue of #22418. Port
ScalarSubqueryExprto use thetry_to_proto/try_from_protohooks added in #21929.Replace the
ScalarSubqueryExprarm indatafusion/proto/src/physical_plan/{to_proto,from_proto}.rswithtry_to_proto/try_from_protoimpls next toScalarSubqueryExpr. See theColumn/BinaryExprmigrations in #21929 for reference.