--markdown option for outputting in triple backtick code blocks

[Arun-42]

I usually use the chat interface and pass my files wrapped in triple back-ticks like (```python). A --format-codeblock option could be the interface.

[simonw]

Oh that's really interesting - so everything you pass in gets wrapped in:

```python
# File name goes here
import os
...
```

We could guess the tags (python or javascript or whatever) based on file extensions. Just a short list of common ones - anything unknown gets triple-backticks with no language tag.

[simonw]

Example output:

test_dir/code.js
```javascript
This is javascript
```
test_dir/code.unknown
```
This is an unknown file type
```
test_dir/python.py
```python
This is python
```
test_dir/python_with_quad_backticks.py
`````python
This is python with ```` in it already
`````

Note how if a file already contains triple or more backticks it gets wrapped in one extra level of backticks.

Here's that example rendered as markdown:

---

test_dir/code.js

This is javascript

test_dir/code.unknown

This is an unknown file type

test_dir/python.py

This is python

test_dir/python_with_quad_backticks.py

This is python with ```` in it already

[simonw]

I'm going to rename this option to --markdown.