OpenSystemsDevelopment / qpdf

* Remove dependency on `perl`, now only required for maintenance
  activities and running the test suite.
* Exercise building qpdf and running executables from JetBrains CLion
  without any special additional tooling beyond pre-built external
  libraries.

This replaces the `copy_dlls` with a powershell script, written mostly
by ChatGPT, starting from the bash script below. The copy_dlls script
had a lot of logic that was no longer needed.

```bash
#!/bin/bash
set -eo pipefail
exe="$1"
dest="$2"
mingw_bin_dir="$3"
if [[ $mingw_bin_dir == "" ]]; then
    echo >&2 "Usage: $(basename $0) exe dest mingw-bin-dir"
    exit 2
fi

get_dlls() {
    objdump -p "$1" | grep 'DLL Name:' | awk '{print $NF}'
}
declare -a dlls
dlls=($(get_dlls "$exe"))
declare -A seen
while [[ ${#dlls[@]} -gt 0 ]]; do
    i="${dlls[0]}"
    dlls=("${dlls[@]:1}")
    if [[ ${seen[$i]} == 1 ]]; then
        continue
    fi
    seen[$i]=1
    full="$mingw_bin_dir/$i"
    if [[ -f "$full" ]]; then
        cp "$full" $dest/
        dlls+=($(get_dlls "$full"))
    fi
done
```

External libraries for Windows are now built automatically in the
qpdf/external-libs repository and include openssl in addition to zlib
and jpeg. Use these, and update the Windows build to build with the
openssl crypto provider by default. We leave the native crypto
provider enabled in case there is a problem with openssl and also to
continue to exercise that code.

Update documentation to reflect that automatically generated files are
committed. Detect when they are outdated if we have the ability to
regenerate them.