Upgrade to Node 16

[ipeychev]

I'm upgrading to Node 16 as discussed here.

• Node 16 will be the minimal supported version
• Typescript was upgraded to "5.4.2"
• The same amount of tests are passing. There are some, like abortMerge, which were failing even before. Fixing them is another story.

[jcubic]

This needs to wait before we fix the CI/CD. One of the test return 401, something probably expired. If I merge this I will have a broken main branch, and I don't want that. But you can merge this to your other PR we will at least know if your code passes the tests that were failing because abortControler missing.

[ipeychev]

yeah, I did, and the test is passing fine.
See the last commits here. And here are the results - test of push is passing successfully.
I also removed the code which was checking whether AbortController is available, or not, and now the test is just instantiating an AbortController.

[seanpoulter]

I'll update this in the GitHub Workflow in #1879.

[seanpoulter]

Hooray.

As a non-blocking suggestion, we could set up ESLint to sort our imports consistently across all files. 🧹