[SDK/CLI] Change flow op class methods to instance methods (microsoft…

…#515)

# Description

Please add an informative description that covers that changes made by
the pull request and link all relevant issues.

# All Promptflow Contribution checklist:
- [x] **The pull request does not introduce [breaking changes]**
- [ ] **CHANGELOG is updated for new features, bug fixes or other
significant changes.**
- [x] **I have read the [contribution guidelines](../CONTRIBUTING.md).**

## General Guidelines and Best Practices
- [ ] Title of the pull request is clear and informative.
- [ ] There are a small number of commits, each of which have an
informative message. This means that previously merged commits do not
appear in the history of the PR. For more information on cleaning up the
commits in your PR, [see this
page](https://github.com/Azure/azure-powershell/blob/master/documentation/development-docs/cleaning-up-commits.md).

### Testing Guidelines
- [ ] Pull request includes test coverage for the included changes.

src/promptflow/promptflow/_sdk/operations/_flow_operations.py

@@ -193,8 +193,7 @@ def _chat(
                 show_step_output=kwargs.get("show_step_output", False),
             )
 
-    @classmethod
-    def _build_environment_config(cls, flow_dag_path: Path):
+    def _build_environment_config(self, flow_dag_path: Path):
         flow_info = yaml.safe_load(flow_dag_path.read_text())
         # standard env object:
         # environment:
@@ -223,8 +222,7 @@ def _build_environment_config(cls, flow_dag_path: Path):
 
         return env_obj
 
-    @classmethod
-    def _dump_connection(cls, connection, output_path: Path):
+    def _dump_connection(self, connection, output_path: Path):
         # connection yaml should be a dict instead of ordered dict
         connection_dict = connection._to_dict()
         connection_yaml = {
@@ -259,8 +257,7 @@ def _dump_connection(cls, connection, output_path: Path):
             f.write(dump_yaml(sorted_connection_dict, sort_keys=False))
         return env_var_names
 
-    @classmethod
-    def _migrate_connections(cls, connection_names: List[str], output_dir: Path):
+    def _migrate_connections(self, connection_names: List[str], output_dir: Path):
         from promptflow._sdk._pf_client import PFClient
 
         output_dir.mkdir(parents=True, exist_ok=True)
@@ -270,7 +267,7 @@ def _migrate_connections(cls, connection_names: List[str], output_dir: Path):
         for connection_name in connection_names:
             connection = local_client.connections.get(name=connection_name, with_secrets=True)
             connection_paths.append(output_dir / f"{connection_name}.yaml")
-            for env_var_name in cls._dump_connection(
+            for env_var_name in self._dump_connection(
                 connection,
                 connection_paths[-1],
             ):
@@ -283,9 +280,8 @@ def _migrate_connections(cls, connection_names: List[str], output_dir: Path):
 
         return connection_paths, list(env_var_names.keys())
 
-    @classmethod
     def _export_flow_connections(
-        cls,
+        self,
         flow_dag_path: Path,
         *,
         output_dir: Path,
@@ -294,14 +290,13 @@ def _export_flow_connections(
 
         executable = ExecutableFlow.from_yaml(flow_file=Path(flow_dag_path.name), working_dir=flow_dag_path.parent)
 
-        return cls._migrate_connections(
+        return self._migrate_connections(
             connection_names=executable.get_connection_names(),
             output_dir=output_dir,
         )
 
-    @classmethod
     def _build_flow(
-        cls,
+        self,
         flow_dag_path: Path,
         *,
         output: Union[str, PathLike],
@@ -327,9 +322,8 @@ def _build_flow(
             generate_flow_tools_json(flow_copy_target)
         return flow_copy_target / flow_dag_path.name
 
-    @classmethod
     def _export_to_docker(
-        cls,
+        self,
         flow_dag_path: Path,
         output_dir: Path,
         *,
@@ -342,7 +336,7 @@ def _export_to_docker(
             encoding="utf-8",
         )
 
-        environment_config = cls._build_environment_config(flow_dag_path)
+        environment_config = self._build_environment_config(flow_dag_path)
 
         # TODO: make below strings constants
         copy_tree_respect_template_and_ignore_file(
@@ -356,9 +350,8 @@ def _export_to_docker(
             },
         )
 
-    @classmethod
     def build(
-        cls,
+        self,
         flow: Union[str, PathLike],
         *,
         output: Union[str, PathLike],
@@ -407,7 +400,7 @@ def build(
         else:
             output_flow_dir = output_dir / "flow"
 
-        new_flow_dag_path = cls._build_flow(
+        new_flow_dag_path = self._build_flow(
             flow_dag_path=flow_dag_path,
             output=output_flow_dir,
             tuning_node=tuning_node,
@@ -418,21 +411,20 @@ def build(
             return
 
         # use new flow dag path below as origin one may miss additional includes
-        connection_paths, env_var_names = cls._export_flow_connections(
+        connection_paths, env_var_names = self._export_flow_connections(
             flow_dag_path=new_flow_dag_path,
             output_dir=output_dir / "connections",
         )
 
         if format == "docker":
-            cls._export_to_docker(
+            self._export_to_docker(
                 flow_dag_path=new_flow_dag_path,
                 output_dir=output_dir,
                 connection_paths=connection_paths,
                 flow_name=flow_dag_path.parent.stem,
                 env_var_names=env_var_names,
             )
 
-    @classmethod
     @contextlib.contextmanager
     def _resolve_additional_includes(cls, flow_dag_path: Path) -> Iterable[Path]:
         if _get_additional_includes(flow_dag_path):