RFR: 8332020: jwebserver tool prints invalid URL in case of IPv6 address binding

[Jaikiran Pai]

Can I please get a review of this change which proposes to address https://bugs.openjdk.org/browse/JDK-8332020?

`jwebserver` when it is launched prints a URL where the server is accessible. When launched using an IPv6 bind address, the printed URL doesn't enclose the IPv6 literal in `[` `]` thus rendering it in the form:

URL http://0:0:0:0:0:0:0:1:8000/

This is an incorrect representation. As noted in RFC-2732 https://www.rfc-editor.org/rfc/rfc2732#section-2, the host literal is expected to be enclosed between `[` and `]`. 

The commit in this PR addresses that issues. A new jtreg test has been introduced to reproduce this issue and verify the fix.

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Commit messages:
 - 8332020: jwebserver tool prints invalid URL in case of IPv6 address binding

Changes: https://git.openjdk.org/jdk/pull/19173/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19173&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8332020
  Stats: 114 lines in 3 files changed: 108 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/19173.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19173/head:pull/19173

PR: https://git.openjdk.org/jdk/pull/19173