1158: Use nginx for kubernetes ingress r=kaiyou a=micw
## What type of PR?
enhancement
## What does this PR do?
Currently, kubernetes uses a complex ingress setting which is not portable across different ingress controllers. This PR simplifies the ingress and delegates everythins special to Mailu to the front container,
### Related issue(s)
- closes#1121
- closes#1117
- closes#1021
- closes#1045
## Prerequistes
- [x] In case of feature or enhancement: documentation updated accordingly
- [x] Unless it's docs or a minor change: add [changelog]
Co-authored-by: Michael Wyraz <michael@wyraz.de>
20e00ac0c4