[Feature Request]: Swarm OnCondition available support a not condition for context variable values

[marklysze]

Is your feature request related to a problem? Please describe.

At the moment the OnCondition's available parameter can take a string to represent a context variable key and it will evaluate that key's value as True to determine if the OnCondition is available for checking.

However, sometimes we want an OnCondition to be available if the context variable value equates to False. For example we may have a context variable key called "is_logged_in" but we want to transfer to an agent if they are not logged in.

I'm proposing a simple solution that allows us to put an exclamation at the start of the string value that represents NOT, e.g. OnCondition(target=authentication_agent, condition="Authenticate the user", available="!is_logged_in")