RFR: 8328648: Remove applet usage from JFileChooser tests bug4150029 [v4]

[Alisen Chung]

> Removing applet usage from manual JFileChooser tests

Alisen Chung has updated the pull request incrementally with one additional commit since the last revision:

  moved create ui code to helper, change test pass check, add mouse release, remove getContentPane

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18415/files
  - new: https://git.openjdk.org/jdk/pull/18415/files/0126af35..5a05f64b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18415&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18415&range=02-03

  Stats: 36 lines in 1 file changed: 16 ins; 12 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/18415.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18415/head:pull/18415

PR: https://git.openjdk.org/jdk/pull/18415