After the jfx15 branch is forked from jfx, we need to change the release version to 16 in the master branch for OpenJFX 16.

We need to update the release values in the following file:

build.properties

Additionally, since this bumps the major version we need to update the following unit test:

modules/javafx.base/src/test/java/test/com/sun/javafx/runtime/VersionInfoTest.java

See https://github.com/openjdk/jfx/blob/master/UPDATING-VERSION.md for details.