RFR: 8226990: GTK & Nimbus LAF: Tabbed pane's background color is not expected one when change the opaque checkbox. [v5]

[Abhishek Kumar]

> JTabbedPane's content area, tab area and tab background color are not as expected when opaque is set to true or false. 
> The proposed fix is to handle the TabbedPane's background color in installed LAFs. Manual test is added to support the fix and there is no regression caused by the fix. 
> 
> Proposed fix is tested in Ubuntu 22.04 and Oracle linux.
> 
> CI link is posted in JBS.

Abhishek Kumar has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:

 - Title Update
 - Text Block and PassFailJFrame update
 - Merge
 - condition combined
 - Remove WindowsLAF check
 - spacing fix
 - TabbedPane background color fix

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17720/files
  - new: https://git.openjdk.org/jdk/pull/17720/files/05573261..563be986

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17720&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17720&range=03-04

  Stats: 1432234 lines in 12032 files changed: 312658 ins; 679613 del; 439963 mod
  Patch: https://git.openjdk.org/jdk/pull/17720.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17720/head:pull/17720

PR: https://git.openjdk.org/jdk/pull/17720