Busybox wget support

[fredrikfoss]

Hi, this pr adds support for Busybox's implementation of wget, which comes
default on Alpine Linux among other. Busybox wget only support POST, but as far
as I could tell wget won't really be called with other methods here. This should
also close #1601. Let me know what you think.

Busybox wget documentation reference:

BusyBox v1.37.0 (2024-11-13 17:39:29 UTC) multi-call binary.

Usage: wget [-cqS] [--spider] [-O FILE] [-o LOGFILE] [--header STR]
        [--post-data STR | --post-file FILE] [-Y on/off]
        [-P DIR] [-U AGENT] [-T SEC] URL...

Retrieve files via HTTP or FTP

        --spider        Only check URL existence: $? is 0 if exists
        --header STR    Add STR (of form 'header: value') to headers
        --post-data STR Send STR using POST method
        --post-file FILE        Send FILE using POST method
        -c              Continue retrieval of aborted transfer
        -q              Quiet
        -P DIR          Save to DIR (default .)
        -S              Show server response
        -T SEC          Network read timeout is SEC seconds
        -O FILE         Save to FILE ('-' for stdout)
        -o LOGFILE      Log messages to FILE
        -U STR          Use STR for User-Agent header
        -Y on/off       Use proxy