Windows support via winget/choco

[trmxvibs]

pkgwrap currently supports 11 Unix-like backends but no native Windows
support. Adding a WindowsBackend (winget or choco) would follow the same
Backend interface in backends/base.py — see apt_backend.py as reference.

Challenges to solve: winget syntax differs (winget install vs apt
install), and Windows has no sudo equivalent (UAC elevation works
differently). Good starting point for anyone comfortable with subprocess

• Windows.

[kaminimangal]

@trmxvibs Can you assign this to me? I'm on Windows myself, so I can test directly. Plan: add a WindowsBackend in backends/base.py style (following apt_backend.py as reference), mapping install/remove to winget. Will handle the UAC elevation difference separately from the sudo pattern used in Unix backends.