Fix Mac package build warnings (QtWebEngine)
Fix Mac package build warnings (QtWebEngine)

There were remnants of manually copying over Qt plugins that had been conditional on NOT APPLE  but became APPLE at some point, and these were causing warnings during package build on the Mac. MacDeployQt handles this so manual copying wasn't needed. Confirmed that with this and other recent changes a clean Mac package build once again produces a working dmg/app.
JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio,JanMarvin/rstudio