Add StateKey

[ro31337]

StateKey is object that represents the key for State object. There can be unlimited number of states (each state object is just a hash). Key is unique identifier used to to retrieve particular state (hash) from the storage.

It should have constructor that accepts parameters:

• platformType - type of the platform
• platformId - unique user identifier for this particular platform
• guid - guid of the object that is using state

Idea is that state can be mixed into any object (as state property). And each menu action for particular user should have its own state. Menu actions can't have the same state for all users (that's why we can't have one guid parameter). State is not shared between users and between commands.

StateKey must have toString method that returns string representation of the key in the following format:

platform_userid_guid

Example:

telegram_31337_4566bd48-d369-4594-aa1e-fb5dae1acf43

Key should be lowercased.