Remove native code that supports UserJvmOptionsService

We removed the Java code that supported the --user-jvm-args CLI arg, and the API supporting UserJvmOptionsService.
We now need to also remove all the native code that is in each native platform to support this functionality.
This included code to read and store user options files, as well as legacy code to read options set by the Java Preference API by javafxpackager in JDK8. Also code to merge user and application level options.