feat(js): move binary operators to beginning of line

[btmills]

When binary expressions span multiple lines, this change moves the operator to the beginning of the second line instead of the end of the first. This fixes #3806.

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory)
• I’ve read the contributing guidelines.

[vjeux]

Hey, I’m sorry but this is a core decision that affects almost every printed line of code and at this point we will not change the existing behavior. This would be a huge breaking change and be way too controversial to everyone using prettier today.

[btmills]

No worries! The original issue was locked, so I couldn’t ask if there was still any interest there, but it was easy enough just to submit a PR. Is there any interest in doing this behind an option instead? I would be happy to at least try adding that to this PR.

[kachkaev]

Something to consider for v2?

[suchipi]

I think at this point it would be more appropriate for this to be in a fork rather than v2 or behind an option, I don't want to invite the onslaught of opinions