add API to dump RepositoryInfo and Project as JSON

**Is your feature request related to a problem? Please describe.**
When filing #2960, I thought it might be worthwhile to dump propertiesl of `RepositoryInfo` and `Project` as JSON (as another endpoint).

**Describe the solution you'd like**
add 2 endpoints to dump the JSON representation of these objects.

**Describe alternatives you've considered**
N/A

**Additional context**
N/A
