Rename lib to utils

[ecraig12345]

Rename all lib folders to utils so we can gitignore lib and use it for build output. (I could use utilities or some other name instead if people prefer.)

Another option is to move the things formerly under packages/react/src/lib to their own package, but that would require significantly more work/breaks.

I did NOT actually add lib to .gitignore yet because I'm concerned that would cause any changes to lib in open PRs to just disappear when they merge with master (instead of being merged into the moved files).

The following open PRs touch files in lib folders: #2115, #2044, #2006, probably #1999, #1991, #1980, #1867, #1301. Other PRs may also add/modify references to lib imports, but this will be caught by a merge conflict and/or build error.

Microsoft Reviewers: Open in CodeFlow

[ecraig12345]

The formatting changes here are because I have my editor set up to run prettier on save (could revert if desired). Same in a couple other markdown files.

[kenotron]

I think we should revert this - danger actually checks for diffs. So this will blow up danger.

[ecraig12345]

Not quite sure what you mean about danger?

[kenotron]

I think the only thing I want to mention is to preserve the CHANGELOG.md formatting for now - maybe we should have added CHANGELOG.md in .prettierignore

[kenotron]

I think we should revert this - danger actually checks for diffs. So this will blow up danger.

[layershifter]

Not sure that this is a really breaking change as I don't see anything that can affect consumer that uses public API.

[ecraig12345]

That's good to know, thank you! Some of my experience with Fabric has led me to be very cautious about assuming internal path changes are non-breaking, but if you think it's safe here that's great.