RFR: 8238080: FXMLLoader: if script engines implement javax.script.Compilable compile scripts

[Rony G.Flatscher]

This WIP adds the ability for a fallback in case compilation of scripts fails, in which case a warning gets issued
about this fact and evaluation of the script will be done without compilation. Because of the fallback scripts get
compiled with this version by default. It extends PR 187 <https://github.com/openjdk/jfx/pull/187>.

To further ease spotting scripts that cause a ScriptException a message in the form of "filename: caused
ScriptException" gets added to the exception handling in either of the three locations: an error message, a stack trace
or a wrap-up into a RuntimeException (having three different kinds of reporting ScriptExceptions may be questioned,
however none of these tear down the FXML GUI).

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Commit messages:
 - Document the compile processing instruction for scripts.
 - Add missing language processing instruction.
 - Correct typo, replace tabs, remove trailing blanks.
 - Make sure we test the default behaviour to compile script by leaving out the compile PI.
 - Revert temporary rename of test method.
 - Correct ModuleLauncherTest (remove non-existing test), correct formatting.
 - Always supply the script's filename in the error message first to further ease spotting the location of script exceptions.
 - Make message more pregnant.
 - Compile by default, have fallback if compilation fails, adapt/add test unig
 - add compile process instruction to control compilation of compilable scripts; PI data can be truei (default) or false
 - ... and 14 more: https://git.openjdk.java.net/jfx/compare/159f6516...44b0f9f8

Changes: https://git.openjdk.java.net/jfx/pull/192/files
 Webrev: https://webrevs.openjdk.java.net/jfx/192/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8238080
  Stats: 2544 lines in 29 files changed: 2514 ins; 2 del; 28 mod
  Patch: https://git.openjdk.java.net/jfx/pull/192.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/192/head:pull/192

PR: https://git.openjdk.java.net/jfx/pull/192