[Feature Request]: Allow easier repository specification in config

### Feature description

Currently, one can specify input repositories like this in the config file:
```yaml
inputRepositories:
- Bioconductor.BioCsoft=https://bioconductor.org/packages/release/bioc
- CRAN=https://cran.rstudio.com
```

We could make it a bit better:
```yaml
inputRepositories:
- name: Bioconductor.BioCsoft
url: https://bioconductor.org/packages/release/bioc
- name: CRAN
url: https://cran.rstudio.com
```

This is easily doable with `viper` and is used for [git-synchronizer config](https://github.com/insightsengineering/git-synchronizer/blob/main/README.md#configuration-file).

After implementing, the `README.md` has to be updated to reflect the change.

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