Make frontend docker config more configurable

This PR makes the docker setup for the frontend configurable.

This PR adds two new configuration variables for the frontend:

This allows multiple images with multiple ports to be deployed on the same server.

I, the author of this PR checked the following requirements for good software quality:

[x] The code is properly formatted (I ran the formatter)
[x] The code is written with our software quality standards (I ran the linter)
[x] The code is written using our code style
[ ] Extensive in source documentation has been added
[ ] Unit and/or integration tests have been added
[ ] All texts have been internationalized with at least the following languages:
- [ ] English
- [ ] German
[ ] I tried addressing all new accessibility problems displayed in the console and documented if they can't be fixed
[ ] I attached performance measurements to prevent performance degradation
[ ] I added the changes to the next release section of the changelog

I, the reviewer checked the following things:

[ ] I ran the software once and tried all new and related functionality to this PR
[x] I looked at all new and changed lines of code and commented on possible problems
[ ] I read the added documentation and checked if it is understandable and clear
[ ] I checked the added tests for completeness
[ ] I checked the internationalized strings for spelling errors
[ ] I checked the performance metrics for problems or unexplained degradation
[ ] I checked that the changes are noted in the changelog

DLR-SC / ESID