Release steps can be improved

[gibson042]

In following MAINTAINERS.md to produce release agoric-upgrade-14-rc1, I observed some opportunities for improvement:

• [feat: Improve release steps #9080] MAINTAINERS.md could be better-formatted, particularly in not breaking list formatting with non-indented content.
• [feat: Improve release steps #9080] It could also provide more guidance on how to check on publication of the expected Docker image.
• Speaking of which, the pre-release Docker image gets published with a "latest" tag... is that really what we want?
• [build: Add a gen-github-release.sh script for generating GitHub release contents #9241] The "Create a GitHub release" step should probably have an actual (and possibly automated) template rather than instructions to use previous releases.
• The "Check the development history oriented release description into the top-level CHANGELOG.md on the base branch" step appears to not have been followed in a while—we should revisit what we actually want here.
• [feat: Improve release steps #9080] Generated tags should all be created in one step, rather than hiding creation of the v… tag inside a get-released-tags script that seems to be locally read-only but is actually not.
• [feat: Improve release steps #9080] npm-dist-tag.sh does a lot, especially in lerna mode, and should support dry-run.
• [feat(scripts): Add npm-dist-tag.sh --otp-stream for a better CLI experience #9658] It also has way too many npm login prompts, and should be updated to behave more like yarn lerna publish --concurrency 1 from-package (which only prompted me once).

[gibson042]

This is pretty much done; anything further merits its own issue.