Edits for tutorial

[jackgerrits]

Why are these changes needed?

• Edits to code executor
• Update getting started
  • Use code executors
  • Remove enhanced inference
  • Update whats next
• Update what's next page

Related issue number

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.