Fix webpack dev builds to compile and consume all packages

[lucas-koehler]

The webpack dev builds currently only consume the host package (e.g. the vanilla renderers) directly. All other packages are consumed as their bundle in their lib folder. Thus, changes are not consumed automatically while the webpack dev server runs.

This should be improved to:

• ignore and not consume built variants of JSON Forms packages
• compile and consume JSON Forms packages when they are changed