[RRFC] remove `npm-shrinkwrap.json` from the list of unignorable files

Motivation ("The Why")

I have npm-shrinkwrap.json in both .gitignore and .npmignore on basically all of my repos. However, I unknowingly broke ls-engines when I published it, not realizing that the npm-shrinkwrap.json i'd been playing with would be published despite being explicitly ignored.

Possible solutions

• allow npm-shrinkwrap.json to be npmignored
• fail a publish when an unignorable file is explicitly ignored, via "files" or ".npmignore" or ".gitignore"

The upsides

• it would be much harder to accidentally break consumers by publishing a shrinkwrap (something that's a long-standing bad practice anyways)

The downsides

• someone who wants to publish a shrinkwrap would only be able to do so if they weren't already explicitly ignoring it.

Can anyone provide any scenario where making one of the above changes would pose problems for someone?

Review the RFC's motivation and the interactions among npm-shrinkwrap.json, .gitignore, .npmignore, and the package "files" setting. A complete contribution would establish whether npm should allow the shrinkwrap to be ignored or reject conflicting publish configuration, with an agreed rationale and scope.