RFR: 8288137: The set of available printers is not updated without application restart [v4]

[Phil Race]

> This fixes the issue that the default printer or set of available printers is fixed from the first call to it in the lifetime of the application.
> Now subsequent calls will check to see if there are changes.
> A manual test is provided for verifying this - it requires you to add/remove printers at the system level to verify anything related to this fix.

Phil Race has updated the pull request incrementally with one additional commit since the last revision:

  8288137

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Changes:
  - all: https://git.openjdk.org/jfx/pull/817/files
  - new: https://git.openjdk.org/jfx/pull/817/files/21ec7bdd..490e17da

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=817&range=03
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=817&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/817.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/817/head:pull/817

PR: https://git.openjdk.org/jfx/pull/817