Fixed React Fiber deprecation of using ref with stateless function components

[oriSomething]

Issue: #1539

In short, React Fiber deprecated the ability to add ref to a stateless function component.

What I did

Converted LeftPanel and Shortcuts from stateless function components to React.Components.
It should be said that it seems the documentations of developing storybook slightly outdated and missing some information.
Another thing to mention is that I had to use eslint-disable for the components since according to some ESLint React plugin rule they shouldn't be a regular React.Component.

I hope I did an okay fix. Please, let me know.

How to test

1. clone the repo with fix
2. run npm install
3. run npm link
4. go to lib/ui and run there npm link
5. go to app/react and over there do the following:
6. run npm i react@next react-dom@next --only=dev
7. run `npm link '@storybook/ui'
8. run npm link

After the flowing you should create a React project using React Fiber.
Needs over there to set-up storybook and then run npm link '@storybook/react'.
The errors for issue #1539 should gone

Fix issue 1539

[oriSomething]

It seems there is no relation to the code and the failing hooks. Can someone from the maintainers have a look?

[oriSomething]

I get this in the page of ci/circleci: build_accept_deploy/deploy

[codecov]

Codecov Report

Merging #1551 into master will decrease coverage by 0.01%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #1551      +/-   ##
==========================================
- Coverage   21.34%   21.32%   -0.02%     
==========================================
  Files         244      244              
  Lines        5378     5378              
  Branches      658      657       -1     
==========================================
- Hits         1148     1147       -1     
- Misses       3730     3744      +14     
+ Partials      500      487      -13

Impacted Files	Coverage Δ
lib/ui/src/modules/ui/components/shortcuts_help.js	40.9% <0%> (-4.55%)	⬇️
...b/ui/src/modules/ui/components/left_panel/index.js	100% <100%> (ø)	⬆️
addons/events/src/components/Event.js	0% <0%> (ø)	⬆️
addons/info/src/components/PropTable.js	22.36% <0%> (ø)	⬆️
addons/storyshots/src/storybook-channel-mock.js	0% <0%> (ø)	⬆️
lib/ui/src/modules/ui/routes.js	0% <0%> (ø)	⬆️
lib/ui/src/modules/ui/configs/handle_routing.js	28.04% <0%> (ø)	⬆️
lib/ui/src/modules/api/configs/init_api.js	40.47% <0%> (ø)	⬆️
lib/ui/src/modules/shortcuts/actions/shortcuts.js	6.25% <0%> (ø)	⬆️
.../ui/src/modules/ui/components/left_panel/header.js	28.57% <0%> (ø)	⬆️
... and 23 more

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[oriSomething]

From what I've checked I've finished the PR a week ago, and since then, I only rebase from master.
Can anyone from the members of the repo tell me if anything else needs to be done? I would be happy if this PR will be merged since I already use React 16

[Hypnosphi]

That's a shame you had no response for so long =(

As for reproduction steps, does it work with npm run bootstrap instead of manual linking?

[Hypnosphi]

Ok, looks like it's ShortcutsHelp that needed to be converted to class. I fixed this. Thanks a lot anyway!