Buildkite integration for Swift project

[oguzkocer]

### Tasks
- [x] Validate Swift package
- [x] Validate Podspec
- [x] Run Lint
- [x] Run unit & integration tests
- [x] Publish the Swift package

[jkmassel]

Validate Swift package
Run Lint
Run unit & integration tests

These were addressed by #35, so I'm checking them off

[jkmassel]

All of these items have been addressed.