RFR: 8274854: Mnemonics for menu containing numeric text not working [v4]

[Michael Strauß]

> This PR fixes an issue with mnemonic parsing by removing the restriction that a mnemonic symbol must be a letter. Now, it can be any character except whitespace.

Michael Strauß has updated the pull request incrementally with four additional commits since the last revision:

 - revert rename
 - revert rename
 - test for KeyCombination
 - renamed TextBinding to MnemonicParser, refactored tests

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/647/files
  - new: https://git.openjdk.java.net/jfx/pull/647/files/c4012056..5b5d720d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=647&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=647&range=02-03

  Stats: 224 lines in 3 files changed: 146 ins; 72 del; 6 mod
  Patch: https://git.openjdk.java.net/jfx/pull/647.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/647/head:pull/647

PR: https://git.openjdk.java.net/jfx/pull/647