RFR: 8351339: WebSocket::sendBinary assume that user supplied buffers are BIG_ENDIAN

[Volkan Yazici]

Fixes endian handling `jdk.internal.net.http.websocket.Frame.Masker`.

### Implementation notes

I deleted the `Frame` clone in tests, and rewired the test code depending on it to the actual `Frame`. To enable this, I relaxed the visibility of the actual `Frame`. I guess the `Frame` clone was introduced to have strict visibility in the actual `Frame`. Though this is not needed since the actual `Frame` is in an internal package. Plus, the fact that bug is in the `Frame` class hints in the direction that there should be one `Frame`.

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

Commit messages:
 - Fix endian handling in `jdk.internal.net.http.websocket.Frame`
 - Replace `jdk.internal.net.http.websocket.Frame` clone with the original one

Changes: https://git.openjdk.org/jdk/pull/24033/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24033&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351339
  Stats: 901 lines in 24 files changed: 235 ins; 584 del; 82 mod
  Patch: https://git.openjdk.org/jdk/pull/24033.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24033/head:pull/24033

PR: https://git.openjdk.org/jdk/pull/24033