Parse the repository specification in the column "Repo" in the register CSV file
Source:R/configuration.R
parse_repository_spec.RdBased roughly on [`remotes::parse_one_extra`](https://github.com/r-lib/remotes/blob/master/R/deps.R#L519)
R/configuration.R
parse_repository_spec.RdBased roughly on [`remotes::parse_one_extra`](https://github.com/r-lib/remotes/blob/master/R/deps.R#L519)