RFR: JDK-8284445: macOS 12 prints a warning when a function key shortcut is assigned to a menu

[vlaaad]

This PR addresses [JDK-8284445](https://bugs.openjdk.org/browse/JDK-8284445).

Context: the warning might be more important than it seems. Our JavaFX-based desktop app has [an issue](https://github.com/defold/defold/issues/7845) — when the user opens 2 instances of the app, one of the instances hangs after a while. While debugging the issue, I found that it's somehow related to the system menu bar — not refreshing it fixes the issue. Further investigations revealed that the app hangs only if we show menus that use F1-F24 shortcuts. This reminded me of the warnings we get about `NSEventModifierFlagFunction specified to -setKeyEquivalentModifierMask` for such shortcuts. I experimented with removing the modifier for these shortcuts, and it helped with our issue!

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Commit messages:
 - 8284445: Don't set function modifier for F1-F24 shortcuts on macOS

Changes: https://git.openjdk.org/jfx/pull/1252/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1252&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8284445
  Stats: 10 lines in 2 files changed: 0 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jfx/pull/1252.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1252/head:pull/1252

PR: https://git.openjdk.org/jfx/pull/1252