RFR: 8320965: Scrolling on a touch enabled display fails on Wayland

[Jose Pereda]

This PR replaces the deprecated `gdk_pointer_grab` with `gdk_seat_grab`, and `gdk_pointer_ungrab ` with `gdk_seat_ungrab`, using runtime checks and wrapped functions for GTK 3.20+ (so systems without it still run with GTK 3.8+), and fixes the dragging issue on Wayland.

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Commit messages:
 - Add wrappers of gdk_seat_grab and gdk_seat_ungrab

Changes: https://git.openjdk.org/jfx/pull/1305/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1305&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320965
  Stats: 96 lines in 5 files changed: 88 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jfx/pull/1305.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1305/head:pull/1305

PR: https://git.openjdk.org/jfx/pull/1305