add queue name to job executor construction context (issue #11)

[Foxcapades]

Description

Adds the name of the source queue to the job executor factory method to provide additional context for creating a JobExecutor instance.

Changes

• Update readme with additional information about implementing the JobExecutor and JobExecutorFactory interfaces
• Clean up imports
• Add missing doc block to JobContext interface
• Add new JobExecutorContext type to provide context to the JobExecutorFactory

PR Checklist

• [x] Updated relevant source docs
• [x] Updated readme / docs
• [x] Updated dependencies