**Apache Airflow version**: 2.1.1

**What happened**:

The rendered templates screen doesn't show the operator arguments for TaskFlow API operators.
![image](https://user-images.githubusercontent.com/72943478/125486179-f6dde0be-9f60-4aca-831a-5cfd16e7f006.png)

**What you expected to happen**:

Should show the arguments after any templates have been rendered.

**How to reproduce it**:

Will happen for any `@task` decorated operator.

**Anything else we need to know**:

This issue appears on a number of operators.  Possible solution is to modify the "get_python_source" in utils/code_utils.py to handle list and dict. This would cause any operator that using py as the renderer to handle lists and dicts.  Possibly something like:
```
    if isinstance(x, list):
        return [str(v) for v in x]

    if isinstance(x, dict):
        return {k: str(v) for k, v in x.items()}
```
The converting values to strings seems necessary in order to avoid errors when this is passed to the pygments lexer.
![image](https://user-images.githubusercontent.com/72943478/125494716-01cf0c11-9e5f-45fa-afe2-4f99409edefc.png)

airflow/www/views.py
"""Autocomplete."""
        query = unquote(request.args.get('query', ''))
        if not query:
            return wwwutils.json_response([])
        
        dag_ids_query = session.query(DagModel.dag_id.label('item')).filter(
            ~DagModel.is_subdag, DagModel.is_active, DagModel.dag_id.ilike('%' + query + '%')
        )
        owners_query = session.query(func.distinct(DagModel.owners).label('item')).filter(
            ~DagModel.is_subdag, DagModel.is_active, DagModel.owners.ilike('%' + query + '%')
        )
        
        status = flask_session.get(FILTER_STATUS_COOKIE)
        if status == 'active':
            dag_ids_query = dag_ids_query.filter(~DagModel.is_paused)
            owners_query = owners_query.filter(~DagModel.is_paused)
        elif status == 'paused':
            dag_ids_query = dag_ids_query.filter(DagModel.is_paused)
            owners_query = owners_query.filter(DagModel.is_paused)
        filter_dag_ids = current_app.appbuilder.sm.get_accessible_dag_ids(g.user)
        dag_ids_query = dag_ids_query.filter(DagModel.dag_id.in_(filter_dag_ids))
        owners_query = owners_query.filter(DagModel.dag_id.in_(filter_dag_ids))
        payload = [row[0] for row in dag_ids_query.union(owners_query).limit(10).all()]
        return wwwutils.json_response(payload)
class DagDependenciesView(AirflowBaseView):