Node now have APIs to convert them to buffer, integer and string. This
allows possibility to handle methods that need explicitly use one of the
overloads instead of integer.
This patch also adds handling of DebugOp. This is used quite heavily in
uACPIs test suite.
Method invocation is starting to come together. This implemenetation
can interpret some of the qemu's functions to enter ACPI mode.
PCI config space access is currently the one thing is between
entering ACPI mode.
