RFR: 8078471: Backspace does not work in JFileChooser with GTK L&F [v5]

[Abhishek Kumar]

> The Backspace key doesn't lead to parent directory of current directory for JFileChooser in GTK LAF. 
> Added the lazy input value in `GTKLookandFeel` and fix is working fine.
> 
> Implemented a manual test to check BackSpace behavior for all installed LAF in Linux platform.
> The test mentioned in [JDK-8078471](https://bugs.openjdk.org/browse/JDK-8078471) `javax/swing/JFileChooser/4150029/bug4150029.html` also working fine with GTK option (-client -Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel).

Abhishek Kumar has updated the pull request incrementally with one additional commit since the last revision:

  Formatting of long lines

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11291/files
  - new: https://git.openjdk.org/jdk/pull/11291/files/3b19e5cd..55540ef9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11291&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11291&range=03-04

  Stats: 11 lines in 1 file changed: 2 ins; 1 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/11291.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11291/head:pull/11291

PR: https://git.openjdk.org/jdk/pull/11291