Julian Amarilla 7fcebf37ec
Fix #15440 default --empty fails at empty streams (#15562)
Fixes #15440 

# Description
Wraps ListStream stream type from `impl Iterator` to `Peekable<impl
Iterator>`, this allows checking for empty streams and treating them as
empty values
 
Example:
```
# previously
$ glob ? | default -e void
> # empty list

$ echo '' | default -e void
> void

####################

# now
$ glob ? | default -e void
> void

$ echo '' | default -e void
> void
```

# User-Facing Changes

empty list streams will behave as `nothing` values when testing for
emptiness

# Tests + Formatting

- Add 2 tests
- clippy OK
- fmt OK

# After Submitting
2025-04-17 16:57:25 +02:00
..

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