Add CRA TypeScript support for .storybook folder

[mrmckeb]

Issue: #4587 (comment)

What I did

Allowed the use of .ts and .tsx files in the .storybook folder. This was not in scope initially, but was added on request.

How to test

When using with CRA and TypeScript, rename your config.js to config.tsx in the .storybook folder.

[mrmckeb]

@igor I found a strange issue, unrelated, where this config is loaded twice - you can see that it's happening because it logs the action twice in the terminal.

I've safeguarded against this for now, but we should look to resolve it - unfortunately I don't have time this weekend. I'll create an issue for it.

[igor-dv]

I found a strange issue, unrelated, where this config is loaded twice

Yeah, it is a "known" thing. We apply presets on defaultConfig and baseConfigbecause we don't know what user will choose. The fix could be only to have a defaultConfig, but for now it's a breaking change and should be discussed...

[codecov]

Codecov Report

Merging #4902 into next will increase coverage by 0.13%.
The diff coverage is 71.42%.

@@            Coverage Diff             @@
##             next    #4902      +/-   ##
==========================================
+ Coverage   34.84%   34.98%   +0.13%     
==========================================
  Files         566      566              
  Lines        7005     7009       +4     
  Branches      937      938       +1     
==========================================
+ Hits         2441     2452      +11     
+ Misses       4064     4060       -4     
+ Partials      500      497       -3

Impacted Files	Coverage Δ
app/react/src/server/framework-preset-cra.js	0% <0%> (ø)	⬆️
app/react/src/server/cra-config.js	47.05% <83.33%> (+19.39%)	⬆️

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[mrmckeb]

@igor-dv Thanks for the feedback. PR updated, and I also added tests.

[igor-dv]

LGTM 💪