RFR: 8368157: DefaultProxySelector should handle ws/wss protocol like the http/https protocol

[EunHyunsu]

DefaultProxySelector.select() returns DIRECT for ws/wss URIs even when proxy properties are set. Since WebSocket tunnels over HTTP/HTTPS, ws/wss should use the same proxy settings.              
                                                                                                                                                                                                    
This normalizes ws to http and wss to https at the top of select(), matching what OpeningHandshake already does internally. Same fix applied to ProxySelector.of(). Javadoc and net-properties.html updated.

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Commit messages:
 - 8368157: DefaultProxySelector should handle ws/wss like http/https

Changes: https://git.openjdk.org/jdk/pull/29882/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29882&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8368157
  Stats: 283 lines in 4 files changed: 274 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/29882.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29882/head:pull/29882

PR: https://git.openjdk.org/jdk/pull/29882