[Feature Request]: Allow easier repository specification in config

[walkowif]

Feature description

Currently, one can specify input repositories like this in the config file:

inputRepositories:
  - Bioconductor.BioCsoft=https://bioconductor.org/packages/release/bioc
  - CRAN=https://cran.rstudio.com

We could make it a bit better:

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.

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

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