v0.2.0

• Breaking: Rename Context.edit_response() to Context.edit_initial_response(). This is to make the purpose of the function clearer.
• Breaking: Remove arc.Injected[T] typehint alias. Use arc.inject() instead. This is to avoid confusion between the two.
• Breaking: Rename GatewayPlugin to GatewayPluginBase and RESTPlugin to RESTPluginBase.
• Add GatewayContext aliasing Context[GatewayClient]
• Add RESTContext aliasing Context[RESTClient]
• Add GatewayPlugin aliasing GatewayPluginBase[GatewayClient]
• Add RESTPlugin aliasing RESTPlugin[RESTClient]
• Add support for passing mappings to choices= when specifying option params.
• Move ABCs used internally under arc.abc.
• Improve handling missing responses via REST by adding NoResponseIssuedError.
• Fix @plugin.inject_dependencies failing when located outside of the main module.