Create `Activity` Class

[collindutter]

• [x] I have read and agree to the contributing guidelines.

Is your feature request related to a problem? Please describe. Right now there is no type available for Tool Activities. This requires us to hackily set and get attributes on Callables Describe the solution you'd like Create an Activity class that contains fields like name, config, is_activity.

Additional context https://github.com/griptape-ai/griptape/pull/1015/files#r1692262326