Upgrade to Jhipster 7.9.3

[rseedorff]

There is a new JHipster release v7.9.2 but it includes a lot of changes. We need to upgrade due to some outdated dependencies also.

[Weltraumschaf]

Jhipster Issue to track blocker progress

[rseedorff]

There is a new patch release:
https://www.jhipster.tech/2022/09/02/jhipster-release-7.9.3.html

[Weltraumschaf]

We identified the Problem which hinders us from upgrading: In the frontend code we rely on some model properties which were never meant to be genenerated. In the Java code they were never generated in the DTOs. In 1:n releations the other side is only accessible in the "owner" side. This is specified by JPA and is so since ever. It was a bug in the JHipser generators that these properties were generated in the TS code. This was fixed in v7.9.2 of JHipster. Sadly we use these properties in lot of places in our custom code.

We need to investigate all the places to see how much effort it is to fix all of them, before we can upgrade.