app: sort es6 imports

[jorgeorpinel]

Currently there's not much order in js file imports. Some files group them with comments or spaces in between e.g.

https://github.com/iterative/dvc.org/blob/9c8cc540cfbd004db9ac3747bd56b6ddc328ed24/pages/doc.js#L3-L24

or

https://github.com/iterative/dvc.org/blob/9c8cc540cfbd004db9ac3747bd56b6ddc328ed24/src/Documentation/SidebarMenu/SidebarMenu.js#L1-L14

I suggest we remove all these comments, which don't really add any value, and apply this ESLint rule: https://eslint.org/docs/rules/sort-imports

[shcheklein]

@jorgeorpinel 👍 let's try.

[jorgeorpinel]

Alright, I added the rule and ran eslint --fix pages src in 327d583 but this only fixes some of the problems found by it. (Prettier/Restyled can't fix this either.)

Most issues have to be solved manually and are still outstanding, so I left the rule with "warn" level (not "error"), so it doesn't make the CI checks fail. This means unfortunately no one will ever notice these warnings (they're not even displayed by lint-staged when it runs ESLint, since warnings don't cause it to exit with a non-zero code and the output is hidden).

Should it be mandatory instead @shcheklein? This way it's really only useful if you manually run yarn lint-check and fix manually.

[jorgeorpinel]

Also, VSCode has a sort-imports extension that fixes the problems eslint --fix can't. We could add it as a recommendation in the docs contrib guide instead, or on top of making the ESLint rule mandatory.

Note that it also applies this and this styles.