RFR: 4346610: Adding JSeparator to JToolBar "pushes" buttons added after separator to edge

[Prasanta Sadhukhan]

Adding buttons in a JToolBar after a JSeparator will push the button to the far right of the frame instead of just after the separator

![image](https://github.com/openjdk/jdk/assets/43534309/7fcad657-493f-4370-b046-b31c212a8aa7)

This is because BasicSeparatorUI does not define a maximum size. This leads to the separator getting all the extra width.
Fix is made to limit the separator's maximum size to the preferred size of corresponding orientation (i.e. width for VERTICAL and height for HORIZONTAL)

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Commit messages:
 - 4346610: Adding JSeparator to JToolBar pushes buttons added after separator to edge
 - 4346610: Adding JSeparator to JToolBar pushes buttons added after separator to edge
 - Merge branch 'master' of github.com:prsadhuk/jdk
 - Merge remote-tracking branch 'upstream/master'
 - Merge remote-tracking branch 'upstream/master'
 - Revert "Fix"
 - Fix

Changes: https://git.openjdk.org/jdk/pull/15054/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15054&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-4346610
  Stats: 127 lines in 2 files changed: 126 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15054.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15054/head:pull/15054

PR: https://git.openjdk.org/jdk/pull/15054