Adds a `--format json` flag to `plugin:list` whose output includes each plugin's install source - for git-based third-party plugins, the git remote URL, the checked-out commit, and the followed branch - so the set of installed plugins can be reconstructed elsewhere.
Closes#8798.
This standardization makes it somewhat easier to read stacktraces as the command names are all uniform, so it will be slightly easier to scan trace output.
While I do not agree with _every_ style change, this will force Dokku to have consistent formatting across all shell scripts, which is arguably a Good Thing™.
The command used to reprocess everything is:
```shell
shfmt -l -bn -ci -i 2 -w .
```
