Moves GenerateResponse and GenerateResponseChunk to their own files

[mbleigh]

Refactoring to better organize the ai package, also moves generateAction into the new generate dir.

Checklist (if applicable):

• Tested (manually, unit tested, etc.)
• Docs updated

[apascal07]

Assuming it's just a move, hard to tell if anything has changed.

[mbleigh]

Assuming it's just a move, hard to tell if anything has changed.

It is, but yes it's hard to tell.