RFR: 8373058: Media crash when playing MP3 over JRT protocol on macOS 26

[Alexander Matveev]

Fixed two crashes:
- `shouldWaitForLoadingOfRequestedResource()` was not synchronized with `dispose()`.
- `AddBand()`, `RemoveBand()` and `MoveBand()` was not synchronized with `ProcessBufferLists()`.

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Commit messages:
 - 8373058: Media crash when playing MP3 over JRT protocol on macOS 26

Changes: https://git.openjdk.org/jfx/pull/2008/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=2008&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373058
  Stats: 102 lines in 3 files changed: 42 ins; 19 del; 41 mod
  Patch: https://git.openjdk.org/jfx/pull/2008.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/2008/head:pull/2008

PR: https://git.openjdk.org/jfx/pull/2008