[Feature] Support submissions with anonymous credentials in ooniprobe CLI

[DecFox]

This issue is about supporting measurement submissions in ooniprobe through anonymous credentials. To this end, the changes required to have this include:

• Support C FFI in the rust passport library: feat: introduce C ffi with mozilla/cbindgen ooniprobe-rs#21
• Have a C client in ooni/probe-cli which can call the rust library to make use of the credential functions: feat: Introduce anonymous credentials submission path for ooniprobe-cli #1787
• Enable submissions with credentials in ooniprobe-cli: feat: Introduce anonymous credentials submission path for ooniprobe-cli #1787