RFR: 8248122: java.base should not handle JavaFX application in a specific way

[Kartik Ohri]

JavaFX is no longer a part of OpenJDK. It makes sense to not treat it specially in the JDK. Hence, refactoring the Launcher class to remove JavaFX specific code.

Further investigation reveals that some JavaFX specific code is also present in the `javadoc` tool. For instance,
https://github.com/openjdk/jdk/blob/master/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/BaseOptions.java#L90-L96
https://github.com/openjdk/jdk/blob/master/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/BaseOptions.java#L347-L353
I think we should remove this code as well and the related tests for it.

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Commit messages:
 - Refactor LauncherHelper to remove JavaFX specific handling

Changes: https://git.openjdk.java.net/jdk/pull/978/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=978&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8248122
  Stats: 156 lines in 1 file changed: 0 ins; 154 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/978.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/978/head:pull/978

PR: https://git.openjdk.java.net/jdk/pull/978