Add release-please for auto release generation

[timfish]

This should match what we did for import-in-the-middle.

It's worth looking back at the PRs when this was added because it took a few attempts!

[trentm]

If/when this is done for release process, the cutarelease task could be removed from the Makefile. Arguably the whole Makefile could be dropped. I added that as a convenience for me, because I tended to use that in various projects of mine. Having the make ... alternatives to npm run ... might just be confusing at this point.