Extend the base-hw Irq_session_component class with _is_msi, _address
and _value variables required to support MSI mode of operation.
Return MSI configuration in info() function if _is_msi is set to true.
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082