Add filter to get all transactions methods

[JohnLZeller]

The Synapse API supports using a filter string in calls to get all transactions, however, this package does not support this feature.

• https://docs.synapsefi.com/reference#view-platform-transactions
• https://docs.synapsefi.com/reference#view-user-transactions
• https://docs.synapsefi.com/reference#view-node-transactions

The API docs show this input as a string, though it's more than that, it should be a valid JSON string. This PR is the barebones approach, user is responsible for making the input a string. An alternative could obviously be to handle JSON serializing the string if it's possible, automatically under the hood. Happy to do that if you'd prefer.

[jenstroeger]

Looks good to me.

[jenstroeger]

@JohnLZeller, thanks for the PR.

The API docs show this input as a string, though it's more than that, it should be a valid JSON string.

Either that, or a JSON-serializable object. And I guess the code would be something along those lines:

if filter is None:
    pass  # No filter, don’t serialize.
elif isinstance(filter, str):
    try:
        _ = json.loads(filter)  # All good, a valid JSON string.
    except json.decoder.JSONDecodeError as e:
        raise ValueError("filter is not a valid JSON string") from e
else:
    try:
        filter = json.dumps(filter)  # All good, a JSON serializable object.
    except TypeError as e:
        raise ValueError("filter is not JSON serializable") from e
# Continue to use `filter` as JSON serialized string.

Happy to do that if you'd prefer.

That’d be great 👍🏼

[JohnLZeller]

@jenstroeger no problem, how's this! :)