RFR: 8318091: Remove empty initIDs functions

[Daniel Jeliński]

The removed functions are empty on all platforms.

This patch also removes calls to `Toolkit.loadLibraries();` in classes that no longer have any native methods. The call was needed to ensure that the native awt library is loaded.

Client libs tests passed.

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Commit messages:
 - Remove TextField_initIDs
 - Remove FileDialog_initIDs
 - Remove Button_initIDs
 - Remove Rectangle_initIDs
 - Remove KeyboardFocusManager_initIDs
 - Remove Color_initIDs

Changes: https://git.openjdk.org/jdk/pull/16372/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16372&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318091
  Stats: 364 lines in 17 files changed: 3 ins; 348 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/16372.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16372/head:pull/16372

PR: https://git.openjdk.org/jdk/pull/16372