error: use error_payload in Lua

In Lua struct error used RTTI to return members of the error
depending on its type. If a field was added to error's payload, it
wasn't visible. The patch makes Lua use error_payload instead of
RTTI. Now if the payload gets a new field, it becomes
automatically visible in Lua without need to introduce a new
method for it.

Part of #5568
Part of #4610
Part of #4907