Reverts nushell/nushell#8310
In anticipation that we may want to revert this PR. I'm starting the
process because of this issue.
This stopped working
```
let-env NU_LIB_DIRS = [
($nu.config-path | path dirname | path join 'scripts')
'C:\Users\username\source\repos\forks\nu_scripts'
($nu.config-path | path dirname)
]
```
You have to do this now instead.
```
const NU_LIB_DIRS = [
'C:\Users\username\AppData\Roaming\nushell\scripts'
'C:\Users\username\source\repos\forks\nu_scripts'
'C:\Users\username\AppData\Roaming\nushell'
]
```
In talking with @kubouch, he was saying that the `let-env` version
should keep working. Hopefully it's a small change.
ef7fbf4bf9