RFR: 8342992: Security manager check should not use deprecated methods

[Kevin Rushforth]

As specified in the security manager removal CSR, [JDK-8341858](https://bugs.openjdk.org/browse/JDK-8341858), JavaFX now checks at startup whether the security manager is enabled and fails fast with an `UnsupportedOperationException` if it is. The check is currently done in the `<clinit>` methods of `PlatformImpl` and `LauncherImpl` by calling the deprecated `System::getSecurityManager` method.

This PR creates a new `SecurityUtility::checkSecurityManager` utility method in `javafx.base` that uses reflection to avoid calling API that is deprecated for removal. I also added a call to `checkSecurityManager` in `ReflectUtil` and `MethodUtil` in `javafx.base` for non-graphical applications that only use `javafx.base`.

-------------

Commit messages:
 - 8342992: Security manager check should not use deprecated methods

Changes: https://git.openjdk.org/jfx/pull/1627/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1627&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342992
  Stats: 89 lines in 5 files changed: 77 ins; 8 del; 4 mod
  Patch: https://git.openjdk.org/jfx/pull/1627.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1627/head:pull/1627

PR: https://git.openjdk.org/jfx/pull/1627