Feature request: recursively trace calls within traced function

Hi, thanks for birdseye!

I often use it to trace a whole flow, e.g a web request, from endpoint to response.
It's especially useful when the flow is complicated and can't be debugged locally.

It can get cumbersome to `@eye` the first function -> run it -> add an `@eye` -> run it again -> add the next `@eye` -> etc.

It would be great if one could e.g
```python
def bar(): ...

def baz(): ...

@deep_eye
def foo(call_bar: bool):
if call_bar:
return bar()
return baz()
```

Which would be equivalent to simply decorating `foo`, `bar` and `baz` with `@eye`.

To avoid exploding, maybe a `@deep_eye(trace_limit=10)` option could be supported.

I know birdseye can trace whole modules, but more often than not, functions call functions from other modules, so I'm imagining a trace of a call tree that spans different modules.

What are your thoughts?

Thanks,
Gilad