RFR: 8154038: Spinner's converter should update its editor [v2]

[Karthik P K]

> When converter was changed, `setText` method of spinner was not invoked to update the spinner text using new converter.
> 
> Added a listener to converter property of `SpinnerValueFactory` to call `setText` so that spinner text is updated using new converter.
> 
> Added unit test to validate the fix. Along with spinner of Double type, added a spinner of Integer type as well so that the fix is validated using 2 types of spinner.

Karthik P K has updated the pull request incrementally with one additional commit since the last revision:

  Address review comments

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1057/files
  - new: https://git.openjdk.org/jfx/pull/1057/files/a45ba023..f4376178

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1057&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1057&range=00-01

  Stats: 31 lines in 2 files changed: 20 ins; 7 del; 4 mod
  Patch: https://git.openjdk.org/jfx/pull/1057.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/1057/head:pull/1057

PR: https://git.openjdk.org/jfx/pull/1057