RFR: 8316025: Use testUI() method of PassFailJFrame.Builder in FileChooserSymLinkTest.java [v3]

[Alexey Ivanov]

> This update to `FileChooserSymLinkTest.java` demonstrates the usage of the `testUI` method of the `PassFailJFrame.Builder` class to streamline creating the UI for manual tests.
> 
> The [`main` method](https://github.com/aivanov-jdk/jdk/blob/cb1835527d718226f1c6fdd85ff5986703ea356f/test/jdk/javax/swing/JFileChooser/FileChooserSymLinkTest.java#L110-L118) is a simple sequence of calls:
> 
> 
>     public static void main(String[] args) throws Exception {
>         PassFailJFrame.builder()
>                       .instructions(INSTRUCTIONS)
>                       .rows(35)
>                       .columns(50)
>                       .testUI(FileChooserSymLinkTest::createTestUI)
>                       .build()
>                       .awaitAndCheck();
>     }
> 
> 
> It's the most streamlined way of creating a manual test.
> 
> This change depends on #15665 and [JDK-8294156](https://bugs.openjdk.org/browse/JDK-8294156) as well as #15661, both of which depend on #15660.

Alexey Ivanov has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 19 commits:

 - Amend indentation of nested <li> elements
 - Merge master
 - 8316025: Update the return type of createTestUI
   
   PassFailJFrame now supports creating a list of test windows
 - Merge branch '8294156-func-manual-TestUI' into 8316025-testUI-SymLinkTest
 - 8294156: Allow creating several test windows
   
   The windows can be positioned in advance, or
   a call back PositionWindows interface can be used
   to define their positions after the instruction UI
   frame is positioned on the screen.
 - Use testUI() and builder pattern to create test UI
 - Remove trailing whitespace
 - Mark the Builder class final
   
   It's not supposed to be extended.
 - Amend message in window closing handler
   
   The WindowClosingHandler is used both for the instruction
   frame and for test UI windows.
   Also add blank lines to separate different parts of the class.
 - Use invokeOnEDT in getInstructionFrameBounds
 - ... and 9 more: https://git.openjdk.org/jdk/compare/c587211b...0f4f67b3

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

Changes: https://git.openjdk.org/jdk/pull/15666/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15666&range=02
  Stats: 123 lines in 1 file changed: 53 ins; 60 del; 10 mod
  Patch: https://git.openjdk.org/jdk/pull/15666.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15666/head:pull/15666

PR: https://git.openjdk.org/jdk/pull/15666