add windows build

[dogboydog]

Not working right now, but it's a start. There's no clear error message I can see in the output

Maybe the install step needs some adjustment on windows?

Closes #5

[bjorn]

The error on the Windows build is:

2024-12-28T01:16:41.1617961Z   image_io.cpp
2024-12-28T01:16:41.6068343Z D:\a\qaseprite\qaseprite\aseprite\third_party\zlib\zlib.h(34,10): error C1083: Cannot open include file: 'zconf.h': No such file or directory [D:\a\qaseprite\qaseprite\build\aseprite\src\doc\doc-lib.vcxproj]
2024-12-28T01:16:41.6069671Z   (compiling source file '../../../../aseprite/src/doc/image_io.cpp')

Which might be related to these earlier messages:

2024-12-28T01:12:13.9906174Z -- Renaming
2024-12-28T01:12:13.9906587Z --     D:/a/qaseprite/qaseprite/aseprite/third_party/zlib/zconf.h
2024-12-28T01:12:13.9907222Z -- to 'zconf.h.included' because this file is included with zlib
2024-12-28T01:12:13.9907809Z -- but CMake generates it automatically in the build directory.

Seems like either CMake didn't generate the zconf.h after all, or the location at which it was generated wasn't added to the include path.

[bjorn]

Alright, at least the MSVC build succeeded, but the install location could be improved:

-- Installing: C:/Program Files (x86)/qaseprite/lib/qaseprite.lib
-- Installing: C:/Program Files (x86)/qaseprite/bin/qaseprite.dll

In our build environment, something is setting a QT_PLUGIN_PATH environment variable, which we could use. I'm not sure why the ${QT_INSTALL_PREFIX}/${QT_INSTALL_PLUGINS} thing doesn't seem to be working on Windows.

[bjorn]

Whoops, after merging this I noticed the "32-bit" build is actually also a 64-bit build. I should have used win32_msvc2019 and not win64_msvc2019_64 when installing Qt 5.15.2 (fixed in #7).