feat: add tenv support

[kvendingoldo]

Checks

• I have searched github.com/withfig/fig/issues and there are no duplicates of my issue
• I have run fig doctor in the affected terminal session
• I have run fig restart and replicated the issue again

Operating system

Linux, MacOs, windows

Expected behaviour

I would like to have tenv (https://github.com/tofuutils/tenv) support by fig.https://github.com/tofuutils/tenv

Actual behaviour

Steps to reproduce

No response

Environment

No response

[Ahmwahd]

Hi

[kvendingoldo]

hi, any news? can i make pr?