Fix _destroy implementation

[hs-kgoriunov]

• Fix NodeReadable._destroy() implementation allowing it to work nicely from within pipeline() helper
• Remove seemingly unused usages of NodeReadable._cancelling and NodeReadable._reading
• Replace this.emit('error', e) with this.destroy(e) as it has a more sophisticated implementation and its usage is recommended by the Node.js docs
• Also, bootstrap testing workflow similar to one from the main repo https://github.com/openpgpjs/openpgpjs/blob/2bc07996fa94b32ef4013ffd2a3bc7a860e7a83a/.github/workflows/node.js.yml and add some basic tests

See the discussion here https://github.com/openpgpjs/openpgpjs/issues/1512

[wyardley]

Any progress / updates on this, and if not, would someone be willing to make any additional needed updates?

[larabr]

@wyardley We're going to release a patch over v0.0.11 which is used by OpenPGP.js v5. However, for the newer releases, we are instead removing support for internal conversions, and we'll only accept WebStreams in input. We should implement that in the next release.

[larabr]

Thanks for investigating the problem and finding the fix @hs-kgoriunov ! I've taken over the PR since we are only going to patch an older version of the lib, as mentioned above 🙂