Add syntax highlighting for code snippets printed by Q Chat

### Checks

- [x] I have searched [github.com/aws/amazon-q-developer-cli/issues](https://github.com/aws/amazon-q-developer-cli/issues?q=) and there are no duplicates of my issue

### Operating system

Linux 5.10.236-208.928.amzn2int.x86_64 - Amazon Linux 2

### Expected behaviour

Code snippets have syntax highlighting. This would greatly improve the developer experience, by making the code easier to understand/review.

### Actual behaviour

Q Chat prints green-on-black code snippets. This monochrome output is difficult to parse visually, in particular when we are used to editors/IDEs with built-in syntax highlighting.

### Steps to reproduce

Just ask Q Chat for some code snippet: