Allow forced renders in @storybook/html

[dwightjack]

Issue: #5017

What I did

This PR adds the ability to setup an html object parameter to control whether force re-renders are allowed or not like this:

// .storybook/config.js
import { configure, addParameters } from '@storybook/html';

addParameters({
  html: {
    preventForcedRender: false, // or true
  }
});

// ...

This addresses a change introduced in #4822. I understand the rationale around it, but right now it is just preventing @storybook/html to re-render stories returning a DOM node, which looks much more like a bug than a feature on normal use cases.

How to test

I added a test story in examples/html-kitchen-sink/stories/addon-knobs.stories.js (Addons > Knobs > DOM) and the relevant configuration to examples/html-kitchen-sink/.storybook/config.js

[codecov]

Codecov Report

Merging #6190 into next will decrease coverage by <.01%.
The diff coverage is 0%.

@@           Coverage Diff            @@
##            next   #6190      +/-   ##
========================================
- Coverage   37.9%   37.9%   -0.01%     
========================================
  Files        645     645              
  Lines       9642    9643       +1     
  Branches     354     354              
========================================
  Hits        3655    3655              
- Misses      5940    5941       +1     
  Partials      47      47

Impacted Files	Coverage Δ
app/html/src/client/preview/render.js	0% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 934da0d...4b9ec19. Read the comment docs.

[codecov]

Codecov Report

Merging #6190 into next will decrease coverage by <.01%.
The diff coverage is 0%.

@@           Coverage Diff            @@
##            next   #6190      +/-   ##
========================================
- Coverage   37.9%   37.9%   -0.01%     
========================================
  Files        645     645              
  Lines       9642    9643       +1     
  Branches     354     354              
========================================
  Hits        3655    3655              
- Misses      5940    5941       +1     
  Partials      47      47

Impacted Files	Coverage Δ
app/html/src/client/preview/render.js	0% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 934da0d...4b9ec19. Read the comment docs.

[ndelangen]

@Atekon I think this is good to merge, but after releasing this you'll likely have to update your stories.

Technically a breaking change. WDYT, about releasing this in 5.1 though?