OSX: add entitlements.plist (only for bundle cpack generator)

[mgerhardy]

we are currently using the dragndrop cpack generator - because I have not yet found out how to create one app bundle per component. But once this is done, I will also add the entitlements.

• https://cmake.org/cmake/help/v3.7/module/CPackBundle.html
• https://developer.apple.com/documentation/bundleresources/entitlements

CPACK_BUNDLE_APPLE_ENTITLEMENTS

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>com.apple.security.network.client</key>
        <true/>
        <key>com.apple.security.network.server</key>
        <true/>
        <key>com.apple.security.files.user-selected.read-write</key>
        <true/>
        <key>com.apple.security.files.downloads.read-write</key>
        <true/>
</dict>
</plist>