**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
"""Customize permission names for FAB's builtin UserDBModelView."""
    _class_permission_name = permissions.RESOURCE_USER
    class_permission_name_mapping = {
        'resetmypassword': permissions.RESOURCE_MY_PASSWORD,
        'resetpasswords': permissions.RESOURCE_PASSWORD,
        'userinfoedit': permissions.RESOURCE_MY_PROFILE,
        'userinfo': permissions.RESOURCE_MY_PROFILE,
    }
    method_permission_name = {
        'add': 'create',
        'userinfo': 'read',
        'download': 'read',
        'show': 'read',
        'list': 'read',
        'edit': 'edit',
        'resetmypassword': 'read',
        'resetpasswords': 'read',
        'userinfoedit': 'edit',
        'delete': 'delete',
    }
    base_permissions = [
        permissions.ACTION_CAN_CREATE,
        permissions.ACTION_CAN_READ,
        permissions.ACTION_CAN_EDIT,
        permissions.ACTION_CAN_DELETE,
    ]
    @property
    def class_permission_name(self):