remove formatting lint rules

[zepumph]

We roped those into the main rules a long time ago, so let's get rid of them. Found this issue from #1415.

[zepumph]

These were the only rules we might want to keep:

    // enforce newline at the end of file, with no multiple empty lines
    'eol-last': [ 'error', 'never' ],

    // enforces empty lines around comments
    // PhET devs do not want this to be so strict in general
    'lines-around-comment': [ 'error', { beforeLineComment: true } ]

I would love to have the line before a comment, but other devs don't agree with this, and in fact, there are spots where I also like tucking a comment under a code line (like under an else{} clause). So I think we should not keep this around.

For eol-last, it seems like a nice and easy thing to keep around. I think it would be easy to turn on with a --fix. I'll make a new issue.