build: install 256x256 png icons

This is required by `go-appimage` - and apparently(?) a requirement by
XDG, with SVGs being optional

Signed-off-by: Seth Flynn <getchoo@tuta.io>

CMakeLists.txt

@@ -406,6 +406,7 @@ elseif(UNIX)
     install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${Launcher_Desktop} DESTINATION ${KDE_INSTALL_APPDIR})
     install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${Launcher_MetaInfo} DESTINATION ${KDE_INSTALL_METAINFODIR})
     install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${Launcher_SVG} DESTINATION "${KDE_INSTALL_ICONDIR}/hicolor/scalable/apps")
+    install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${Launcher_PNG_256} DESTINATION "${KDE_INSTALL_ICONDIR}/hicolor/256x256/apps" RENAME "${Launcher_AppID}.png")
     install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${Launcher_mrpack_MIMEInfo} DESTINATION ${KDE_INSTALL_MIMEDIR})
 
     install(FILES "${CMAKE_CURRENT_SOURCE_DIR}/launcher/qtlogging.ini" DESTINATION "share/${Launcher_Name}")

program_info/CMakeLists.txt

@@ -29,6 +29,7 @@ set(Launcher_SVGFileName "${Launcher_SVGFileName}" PARENT_SCOPE)
 set(Launcher_Desktop "program_info/${Launcher_AppID}.desktop" PARENT_SCOPE)
 set(Launcher_mrpack_MIMEInfo "program_info/modrinth-mrpack-mime.xml" PARENT_SCOPE)
 set(Launcher_MetaInfo "program_info/${Launcher_AppID}.metainfo.xml" PARENT_SCOPE)
+set(Launcher_PNG_256 "program_info/${Launcher_AppID}_256.png" PARENT_SCOPE)
 set(Launcher_SVG "program_info/${Launcher_SVGFileName}" PARENT_SCOPE)
 set(Launcher_Branding_ICNS "program_info/prismlauncher.icns" PARENT_SCOPE)
 set(Launcher_Branding_ICO "program_info/prismlauncher.ico")