chore: using typedoc to auto generate docs

[nicholasgriffintn]

In this PR, we are using the package typedoc to automatically generate documentation from our TypeScript files, which will allow us to:

• Simplify the readme as currently everything has to go there and it can be hard to understand
• Remove the requirement to manually update the documentation, outside of adding comments to your code
• Adds more documentation within the code itself as this is how the docs are generated
• Creates a homepage for sqs-consumer, where we could provide more information about functionality in the future

Changes

• Added a workflow to automatically deploy the docs when deployed to main
• Added the dependency typedoc to generate the docs
• Added comments to the code to document the type definitions and functionality - basic
• Cleaned up the README (hopefully https://bbc.github.io/sqs-consumer/ is our GitHub Pages domain)