Buildkite integration for Rust project

[oguzkocer]

### Tasks
- [x] Build the project for all relevant architectures
- [x] Run unit tests
- [x] Generate docs (Don't publish until the project is open source: #16)
- [x] Run `clippy`
- [x] Run `rustfmt`

[jkmassel]

Run unit tests
Run clippy

These are addressed by #35

Run rustfmt

This is addressed by #47

[jkmassel]

Generate docs

#55 should handle this

[jkmassel]

Build the project for all relevant architectures

I think we have this for Rust-specific needs. #13 and #14 address the specific architectures needed for Kotlin / Swift, so I'd be ok to check that item off and close this issue.