bitbake: fetch2: add the npmsw fetcher

This commit adds a new npmsw fetcher that fetches every npm dependencies
described in a npm shrinkwrap file:

  https://docs.npmjs.com/files/shrinkwrap.json.html

The main package must be fetched separately:

  SRC_URI = "npm://registry.url;package=foobar;version=1.0.0 \
             npmsw://${THISDIR}/npm-shrinkwrap.json"

Since a separation has been created between the package and its
dependencies, the package can also be fetched with a non npm fetcher
without impacting the general behavior:

  SRC_URI = "git://github.com/foo/bar.git;protocol=https \
             npmsw://${THISDIR}/npm-shrinkwrap.json"

(Bitbake rev: f5223be54450bf20e0bfbd53b372a7748a44b475)

Signed-off-by: Jean-Marie LEMETAYER <jean-marie.lemetayer@savoirfairelinux.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/__init__.py

@@ -1894,6 +1894,7 @@ from . import osc
 from . import repo
 from . import clearcase
 from . import npm
+from . import npmsw
 
 methods.append(local.Local())
 methods.append(wget.Wget())
@@ -1912,3 +1913,4 @@ methods.append(osc.Osc())
 methods.append(repo.Repo())
 methods.append(clearcase.ClearCase())
 methods.append(npm.Npm())
+methods.append(npmsw.NpmShrinkWrap())