This adds a basic template crate, which will be useful for new
developers to understand how things work and layout all basic stuff they
are expected to write to make it work.

The current implementation just parses all the requests from the
virtqueue and prints the number of descriptor chains and size of each
descriptor buffer in there.

This adds basic sanity tests as well for the same, which can be run to
test the working of the crate.

Signed-off-by: Viresh Kumar <[email protected]>