Per notebook requirements.txt

Is davos would be something to help us to setup per notebook venv? e.g. in https://github.com/dandi/example-notebooks/ we have some notebooks with specific requirements.txt:

```
❯ find -iname requirements.txt
./000055/BruntonLab/peterson21/requirements.txt
./000006/DataJoint/DJ-NWB-Economo-2018/requirements.txt
./000009/DataJoint/DJ-NWB-Guo-Inagaki-2017/requirements.txt
./000010/DataJoint/DJ-NWB-Li-Daie-2015-2016/requirements.txt
./000013/DataJoint/DJ-NWB-Hires-Gutnisky-2015/requirements.txt
```
and it would be great if we could just use smth like

```
import davos
davos.configure(requirements='requirements.txt')
```

and then `davos` would do the magic to ensure that all followup imports would happen from the environment which was configured according to that `requirements.txt`. Is that possible?

backref on issue which inspired the question: https://github.com/dandi/handbook/pull/95

Start with the proposed davos.configure(requirements='requirements.txt') entry point and the per-notebook requirements.txt examples in the issue. Determine whether a notebook-specific environment can be configured so follow-up imports use it; done means those imports resolve according to the selected requirements file.

Written by the indexing model from the issue text.