RFR: 8328562: Convert java/awt/InputMethods/DiacriticsTest/DiacriticsTest.java applet test to main [v2]

[Alexander Zvegintsev]

> Test converted to main.
> Instructions split to Windows and Linux, with some clarifications.
> The test runs successfully on Windows and Linux.

Alexander Zvegintsev has updated the pull request incrementally with one additional commit since the last revision:

  minor spacing

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/18388/files
  - new: https://git.openjdk.org/jdk/pull/18388/files/73d2d47d..6a6e11ab

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18388&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18388&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18388.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18388/head:pull/18388

PR: https://git.openjdk.org/jdk/pull/18388