Add basic typings for the global strapi class

[Convly]

What does it do?

Add a first basis for the Strapi class typings. This is only the first iteration and it is likely to evolve in the next beta releases.

Why is it needed?

Without proper typings, using Strapi with TS is hard and doesn't make a lot of sense.

How to test it?

Create a typescript project and try using the Strapi type exported from @strapi/strapi

[Convly]

Note: In the future, we'll work on providing types for more layers & will start to replace the "unknown" typings with more explicit ones.

[codecov]

Codecov Report

Merging #13281 (40dede5) into features/typescript (3f53cff) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

@@                   Coverage Diff                   @@
##           features/typescript   #13281      +/-   ##
=======================================================
- Coverage                48.23%   48.20%   -0.04%     
=======================================================
  Files                      245      251       +6     
  Lines                     8782     8954     +172     
  Branches                  1960     2008      +48     
=======================================================
+ Hits                      4236     4316      +80     
- Misses                    3735     3820      +85     
- Partials                   811      818       +7     

Flag	Coverage Δ
unit	48.20% <100.00%> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
packages/core/admin/server/services/user.js	83.49% <ø> (ø)
...erver/services/schema-builder/component-builder.js	14.03% <ø> (ø)
...er/services/schema-builder/content-type-builder.js	8.73% <ø> (ø)
...pe-builder/server/services/schema-builder/index.js	10.14% <ø> (ø)
...r/server/services/schema-builder/schema-handler.js	3.57% <ø> (ø)
packages/core/upload/server/bootstrap.js	66.66% <ø> (-3.61%)	⬇️
packages/core/utils/lib/hooks.js	89.65% <ø> (ø)
packages/core/utils/lib/sanitize/index.js	53.84% <ø> (-5.25%)	⬇️
.../server/services/helpers/build-component-schema.js	90.62% <ø> (ø)
.../services/helpers/utils/clean-schema-attributes.js	14.70% <ø> (ø)
... and 18 more

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[Bassel17]

LGTM 👍

[strapi-bot]

This pull request has been mentioned on Strapi Community Forum. There might be relevant details there:

https://forum.strapi.io/t/strapi-v4-2-0-fourth-beta-for-typescript-support/18869/1