Add configuration options to generate graphql schema + types

[Convly]

What does it do?

Adds a artifacts attribute in the GraphQL plugin configuration that allows generating artifacts (GraphQL schema & types definitions) for ou application.
Also, add a generateArtifacts config option to allow or not the generation of such artifacts. The default value is true in dev ENV and false otherwise.

A documentation PR will follow soon.

Why is it needed?

In V3 it was possible to extract our GraphQL schema.

How to test it?

src/config/plugins.js

'use strict';

const { join } = require('path');

module.exports = () => ({
  // ...
  graphql: {
    enabled: true,
    config: {
      generateArtifacts: true,
      artifacts: {
        schema: join(__dirname, '..', 'schema.graphql'),
        typegen: join(__dirname, '..', 'types.d.ts'),
      },
    }
  }
})

Related issue(s)/PR(s)

Fix #12420

[codecov]

Codecov Report

Merging #12467 (96aee20) into master (e5402d0) will not change coverage.
The diff coverage is n/a.

❗ Current head 96aee20 differs from pull request most recent head 97254f8. Consider uploading reports for the commit 97254f8 to get more accurate results

@@           Coverage Diff           @@
##           master   #12467   +/-   ##
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  Coverage   47.64%   47.64%           
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  Files         210      210           
  Lines        8177     8177           
  Branches     1849     1849           
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  Hits         3896     3896           
  Misses       3520     3520           
  Partials      761      761           

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[petersg83]

It looks good to me :)
I put a suggestion for a line but feel free to ignore it

[alexandrebodin]

Any tests you can add ?

Missing tests

[strapi-bot]

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

https://forum.strapi.io/t/v4-graphql-type-definitions-are-not-generated/13470/11