add option to disable line numbers in `view` tool output

I imagine the only avenue for this is CLI argv at process spawn (via `new CopilotClient` construct)

The tool should report the starting line number and the content, allowing clients to display/wrap as needed.
As it is, the output is (sometimes) visually correct but makes for invalid text-selection for code copy/paste.

Also, current line-numbering doesn't account for max-width of numbers

```
9. // example
10. // example
```