Fix STK rawwave installation in Windows builds

[PhysSong]

Fixes #6464.
This PR also makes the rawwave installation handled by CMake scripts on macOS.

[superpaik]

Tested ok with both MSVC and MINGW builds installations

[tresf]

Tested on MacOS, rawwaves exists, has the relevant .raw files, Mallets tested and working.

[tresf]

Fixes #6464. This PR also makes the rawwave installation handled by CMake scripts on macOS.

Curious, why not do the same for Linux?

lmms/cmake/linux/package_linux.sh.in

Lines 110 to 112 in b322f80

	# Copy rawwaves directory for stk/mallets
	mkdir -p "${APPDIR}usr/share/stk/"
	cp -R /usr/share/stk/rawwaves/ "${APPDIR}usr/share/stk/"

[PhysSong]

Curious, why not do the same for Linux?

Because LMMS uses system-wide installation of rawwaves when installed locally, and I didn't wanted to change that behavior. Please suggest me any ideas, if you have one.

[tresf]

Because LMMS uses system-wide installation of rawwaves when installed locally

I had forgotten about local installs.

Please suggest me any ideas, if you have one.

This is a good question. I suppose the installation would be copying over itself for local installs, however when using a custom install prefix, it would not be redundant.

I suppose it's justified to keep this task in the .AppImage script for now, however it may be beneficial as a long -term goal to accommodate this in CMake.