[Feature Request] Scaffolding and bare-bones client

[cretz]

Describe the solution you'd like

Need the scaffolding and initial client for this repo. Namely:

• Scaffolding. Includes:
  • Proto gen, build, lint, docs, test, etc tasks
  • GitHub actions workflow
  • Basic README updates
• Ruby/Rust bridge
• Bare-bones start/exec-workflow-only client. Includes:
  • Starting/executing a workflow from a string only
  • Connection and minimal raw gRPC service calls
  • Workflow handle
  • Basic interceptor
  • Simple test
  • Bare-bones data conversion
  • Bare-bones error hierarchy
  • Yard doc for all API
• Test setup. Includes:
  • Testing infra/tasks
  • Workflow environment w/ local ephemeral server
  • Golang kitchen-sink worker

What will not be included in this initial PR:

• Full RBS signatures
• Full gRPC service call set
• Failure conversion
• Full error hierarchy
• Payload codecs
• Runtime telemetry
• Tests for anything but starting a workflow and getting successful results

Much of this leans on the great work by @antstorm