Restructure packages

[jcomack]

Summary

This PR can be summarized in the following changelog entry:

• Restructures the folders in the monorepo to ensure they are more uniform.

Relevant technical choices:

• This PR introduces a restructuring of the packages, making it more uniform throughout.
  The reasoning behind this, is that if we want to be able to publish the packages as 'normal' packages, we'll have to figure out a way to babelify the packages before they are hosted on NPM.

Test instructions

This PR can be tested by following these steps:

• Ensure tests and example applications remain functioning.

Impact check

• This PR affects the following parts of the plugin, which may require extra testing:
  • As it touches every package and the apps, it's necessary to ensure all tests pass.
  • As building of the packages seems to be offloaded to the plugin, this hasn't been extensively tested yet and might also be impacted.

UI changes

• This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Quality assurance

• I have tested this code to the best of my abilities
• I have added unittests to verify the code works as intended

Fixes #