feat: use purl for package lookups (#2041)

lib/manager/meteor/index.js

lib/manager/npm/index.js

lib/manager/npm/package.js

lib/workers/repository/process/fetch.js

lib/workers/repository/process/lookup/filter.js

lib/workers/repository/process/lookup/index.js

lib/workers/repository/process/lookup/range.js

lib/workers/repository/process/lookup/rollback.js

test/manager/npm/__snapshots__/package.spec.js.snap

test/manager/npm/package.spec.js

...rkers/repository/process/__snapshots__/fetch.spec.js.snap

test/workers/repository/process/fetch.spec.js

...epository/process/lookup/__snapshots__/index.spec.js.snap

test/workers/repository/process/lookup/index.spec.js

test/workers/repository/process/lookup/range.spec.js