recipetool: create: npm: Add support for the new format of the shrinkwrap file

The shrinkwrap file changed its format, but npm does not version this file. So we can use it properly.
The actual changes make the script check if the npm package has dependencies in the actual shrinkwrap format.

Signed-off-by: BELOUARGA Mohamed <m.belouarga@technologyandstrategy.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>