Use Node 22 for chaincode Docker image

[bestbeforetoday]

Closes #435

[bestbeforetoday]

Waiting for a version of Node 22 (and accompanying Docker image) to be released that bundles npm 10.9.1 or later, due to bugs in npm and Node that can cause hangs (or at least very long delays) during dependency installation.

[denyeart]

Waiting for a version of Node 22 (and accompanying Docker image) to be released that bundles npm 10.9.1 or later, due to bugs in npm and Node that can cause hangs (or at least very long delays) during dependency installation.

I approved but wasn't going to merge yet due to this comment. But the auto-merge kicked in. Did you intend to merge it at this time?

[bestbeforetoday]

It's fine to merge now. I'll just want the new Node version to appear before publishing a release. A fixed npm version is already available, just not included in the Node Docker image yet.