Set tokens as json strings in io_config.yaml

[g-gilchrist]

Is your feature request related to a problem? Please describe.
Currently to pass a token that is not a file into io_config, for instance GOOGLE_SERVICE_ACC_KEY,
you must create all the keys value pairs under GOOGLE_SERVICE_ACC_KEY from inside the token.
Due to the current logic the key must be manipulated externally, it would be more beneficial for
automated key rotation, to pass in the key as a JSON string and have the backend convert the
JSON to a dictionary. This would couple well with AWS Secrets Manager's functionality for
automated key rotation which you already have functionality for.

Describe the solution you'd like
I think for someone who knows the code base it would be a relatively simple modification or addition
to take the JSON string and convert it into a dictionary for connecting to GCP for Buckets or BigQuery.

Describe alternatives you've considered
you could try json.loads on the JSON string to convert to a dictionary, or parse it.

[g-gilchrist]

I'm not super familiar with this codebase, but I believe if you look in config.py you can modify the last function to read:

    def __traverse_verbose_config(self, key: Union[ConfigKey, str]) -> Any:
        """
        Traverses a configuration file in verbose format to fetch the
        value if exists; else returns None.
        """
        keys = self.KEY_MAP.get(key)
        if keys is None:
            return None
            
        # this adds the additional functionality
        if isinstance(keys,str):
            keys = json.loads(keys)
            
        branch = self.config
        for key in keys:
            if branch is None:
                return None
            branch = branch.get(key)
        return branch

[g-gilchrist]

I have not tested the code above and could certainly be wrong