Fix tsconfig resolution in Nextjs projects

[valentinpalkovic]

Closes N/A

What I did

I have fixed the way how we try to resolve the app's tsconfig.json. In monorepositories very likely each app/lib has its own tsconfig file, which extends the base root config. In this case, we DON'T want to load the root tsconfig file, but the app/lib config file instead. The resolution algorithm now searches for the following paths in the mentioned order:

• <cwd>/<project>/.storybook/tsconfig.json
• <cwd>/<project>/tsconfig.json
• <cwd>/tsconfig.json

How to test

1. Checkout https://github.com/mandarini/nx-next-storybook-paths
2. Copy/Paste @storybook/nextjs dist folder into project.
3. npx nx build-storybook next-app shouldn't fail

Checklist

• Make sure your changes are tested (stories and/or unit, integration, or end-to-end tests)
• Make sure to add/update documentation regarding your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Maintainers

• If this PR should be tested against many or all sandboxes,
  make sure to add the ci:merged or ci:daily GH label to it.
• Make sure this PR contains one of the labels below.

["cleanup", "BREAKING CHANGE", "feature request", "bug", "documentation", "maintenance", "dependencies", "other"]

[mandarini]

Works as expected now!!! THANK YOU SO MUCH!!!!!

[yannbf]

LGTM!

[shilman]

@valentinpalkovic @yannbf do you want this to be patched back to 7.0.x? If so, please label with patch