RFR: 8286620: Create regression test for verifying setMargin() of JRadioButton [v2]

[Tejesh R]

> Added test for checking setMargin() of JRadioButton.

Tejesh R 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 ten additional commits since the last revision:

 - Updated based on review comments
 - Merge branch 'master' of https://git.openjdk.java.net/jdk into branch_8286620
 - Moving bug4380543.java from closed to open
 - Merge branch 'master' of github.com:TejeshR13/jdk
 - Merge branch 'openjdk:master' into master
 - Merge remote-tracking branch 'upstream/master'
 - Merge remote-tracking branch 'upstream/master'
 - Merge branch 'master' of github.com:TejeshR13/jdk
 - Initial Commit.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8721/files
  - new: https://git.openjdk.java.net/jdk/pull/8721/files/0c5ff984..2635e935

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8721&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8721&range=00-01

  Stats: 456757 lines in 6203 files changed: 315635 ins; 83038 del; 58084 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8721.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8721/head:pull/8721

PR: https://git.openjdk.java.net/jdk/pull/8721