`issues --pr` and `--commit` always return empty descriptions

[shawnz-swiftly]

When running deepsource issues --pr or deepsource issues --commit, it seems that the description field is always empty. This is because they are populated from the AnalysisIssue explanation field, which seems like it is always empty on the server.

Compare that with deepsource issues --default-branch, which instead populates the description from the Issue shortDescription field. This actually works and shows the descriptions when run with the --verbose flag, as expected.

I'm not sure what the right approach is here -- should --pr and --commit read from the Issue shortDescription field, or should the server be fixed upstream to populate explanation on AnalysisIssues? I am not sure what would be necessary to make the latter change, so I am going to prepare a PR for the former change and you can decide what you'd prefer.

Thanks, Shawn