[jdk21u-dev] RFR: 8328012: Convert InputMethod (/java/awt/im) applet tests to main

[Goetz Lindenmaier]

I backport this for parity with 21.0.9-oracle

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Commit messages:
 - Backport 4f8f48654e500e875d14e6b4707ab654acc59176

Changes: https://git.openjdk.org/jdk21u-dev/pull/2081/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2081&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328012
  Stats: 327 lines in 6 files changed: 157 ins; 170 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2081.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2081/head:pull/2081

PR: https://git.openjdk.org/jdk21u-dev/pull/2081