RFR: 7900303: auto updating components need accessbility control

[Dmitry Bessonov]

The auto-updating component that can be improved in JTHarness UI in terms of accessibility is test run progress bar.

Such progress bars are visible on the main desktop and in test run monitor window.

We should provide a mechanism for the user to hide test run progress bars.

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Commit messages:
 - 7900303: auto updating components need accessbility control

Changes: https://git.openjdk.org/jtharness/pull/82/files
  Webrev: https://webrevs.openjdk.org/?repo=jtharness&pr=82&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7900303
  Stats: 37 lines in 3 files changed: 29 ins; 5 del; 3 mod
  Patch: https://git.openjdk.org/jtharness/pull/82.diff
  Fetch: git fetch https://git.openjdk.org/jtharness.git pull/82/head:pull/82

PR: https://git.openjdk.org/jtharness/pull/82