Fixesnushell/nushell#13207
# Description
This fixes the parsing of command usage when that command comes from a
file with CRLF line endings.
See nushell/nushell#13207 for more details.
# User-Facing Changes
Users on Windows will get correct autocompletion for `std` commands.
Factor the big parts into separate files:
- `state_delta.rs`
- `state_working_set.rs`
- smaller `usage.rs`
This required adjusting the visibility of several parts.
Makes `StateDelta` transparent for the module.
Trying to reduce visibility in some other places