Upgrade capacitor 4 and react-scripts 4

[ieugen]

IMPORTANT - Remove node_modules/ to redownload deps

• React scripts upgrade is a preparation for nodejs lts upgrade (version 18 is LTS as of now)
• We will try react-scripts 5 upgrade later and React upgrade as well
  *Minimum nodejs 12.20 is needed by a capacitor dependency
• eslint 7 is required by react-scripts 4.x
• Removed global declaration for process - fix eslint 7 issue
• Because of the upgrades, some deps PR's will be made obsolete

References

• https://github.com/facebook/create-react-app/blob/main/CHANGELOG-4.x.md
• https://eslint.org/docs/latest/user-guide/migrating-to-7.0.0
• https://capacitorjs.com/docs/updating/4-0

[munen]

This looks good to me. It works locally. And as a test, I've deployed it to Staging, already. On first tests on FF/Linux, everything seems to continue to work.

Since packaging organice into a native app is a major effort, this is how I'll structure the existing work for future reviews:

1. I'll merge this PR to develop. Future PRs regarding mobile app integration can also be done against develop.
2. Directly afterwards, I'll create a separate PR from develop into a new feature branch against master describing what has happened so far.
3. This new feature PR will be part of a bigger milestone 'native-app.
4. These feature PRs are mainly due to the fact that the current develop is not 100% finished and reviewed.