RFR: 8209137: Add ability to bind to specific local address to HTTP client [v9]

[Jaikiran Pai]

> This change proposes to implement the enhancement noted in https://bugs.openjdk.java.net/browse/JDK-8209137.
> 
> The change introduces a new API to allow applications to build a `java.net.http.HTTPClient` configured with a specific local address that will be used while creating `Socket`(s) for connections.

Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:

  minor - rename variable in test

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6690/files
  - new: https://git.openjdk.java.net/jdk/pull/6690/files/0990e021..c7e50bec

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6690&range=08
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6690&range=07-08

  Stats: 7 lines in 1 file changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6690.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6690/head:pull/6690

PR: https://git.openjdk.java.net/jdk/pull/6690