Add educational notes for actor isolation violations in conformances and overrides

[hborla]

Description

Add educational notes for the following errors

actor_isolated_witness
actor_cannot_conform_to_global_actor_protocol
non_sendable_arg_into_actor
non_sendable_arg_exits_actor
non_sendable_param_in_witness
non_sendable_param_in_override
non_sendable_result_into_actor
non_sendable_result_exits_actor
non_sendable_result_in_witness
non_sendable_result_in_override
non_sendable_result_in_objc
non_sendable_property_exits_actor
non_sendable_property_into_actor
non_sendable_property_in_witness
non_sendable_property_in_override
non_sendable_property_in_objc

Many of these have the same underlying explanation and can probably share an educational note.

Additional information

No response

[Androp0v]

@hborla, I'd like to contribute to this one 😁 Can I get this assigned?

[hborla]

@Androp0v done! Please let me know if you need any help 🙂