Node 10.x outdated: Warnings during build says that nodejs 10.x is deprecated

[aronasorman]

Observed behavior

Node.js 10.x is deprecated and the using the NodeSource repositories to install it in the Docker build produces the following warning

                              DEPRECATION WARNING                            

  Node.js 10.x is no longer actively supported!

  You will not receive security or critical stability updates for this version.

  You should migrate to a supported version of Node.js as soon as possible.
  Use the installation script that corresponds to the version of Node.js you
  wish to install. e.g.

   * https://deb.nodesource.com/setup_12.x — Node.js 12 LTS "Erbium"
   * https://deb.nodesource.com/setup_14.x — Node.js 14 LTS "Fermium" (recommended)
   * https://deb.nodesource.com/setup_16.x — Node.js 16 "Gallium"

  Please see https://github.com/nodejs/Release for details about which
  version may be appropriate for you.

  The NodeSource Node.js distributions repository contains
  information both about supported versions of Node.js and supported Linux
  distributions. To learn more about usage, see the repository:
    https://github.com/nodesource/distributions

Desired behavior

Once Kolibri has been upgraded to Node.js 16, and kolibri-tools released, we should update Studio to Node.js 16. We'll need to update many dependencies as well.

[rtibbles]

Once we release the latest version of kolibri-tools, we should be able to jump to 16.x here - noting that we'd need to update a bunch of JS dependencies at the same time.