Proposal to replace Clang Format with ESLint and Prettier in phosphor-webui

[Derick]

>  If you think the google config
> makes you more efficient, by all means, I can get behind it, that just
> wasn't my experience.

Where I find it valuable is the visual indicators that happen when
integrated into the editor. It helps hunt down small problems that
often cause big issues, but are hard to spot.

> Did you find any patterns that the UI
> consistently got wrong?

Mostly  just inconsistencies in formatting, but there were some
syntax errors that prettier just fixed for us, unnecessary semi-colons
is one example.

> Were there checks that identified real
> functional issues in the webui (memory leaks, bad pages, race
> conditions, ect)

No

> I'm scrolling through your changeset, and most of it seems like
> whitespace.

It was mostly with exception to some syntax errors. In the update
to the Gerrit review, I removed all the files I formatted, so running
eslint on the app folder will reveal them. I will go in and resolve
those issues in a different patch.

> All in all, if this is something you want, I can get behind it.

Thank you! I don't want to stretch this conversation out. I have found
a win-win.
We can keep the formatting in place using clang-format. ESLint can provide
basic fixes, like removing trailing commas and flagging syntax and potential
issues without impacting the build. We can use prettier only for SCSS.