freeze the node_modules tree for better setup reproducibility

[nunoguedelha]

Refer to npm documentation:
https://docs.npmjs.com/cli/v7/configuring-npm/package-lock-json

package-lock.json is automatically generated for any operations where npm modifies either the node_modules tree, or package.json. It describes the exact tree that was generated, such that subsequent installs are able to generate identical trees, regardless of intermediate dependency updates.

This file is intended to be committed into source repositories.

This is supported since npm version 5 (https://nodejs.dev/learn/the-package-lock-json-file). Considering the npm supported versions on Node.js:

• node v4.2.2 : npm v2.14.7
• node v14.17.0: npm v6.14.13

we need to upgrade https://github.com/robotology/yarp.js to support node v14.17.0 (version used on the module openmctStaticServer) or the current latest LTS.

CC @traversaro @S-Dafarra @RiccardoGrieco

[nunoguedelha]

Implemented in #90 .