RFR: 8374754: jtreg failure handler - replace inline javascript and inline event handlers with same origin javascript files [v2]

[Jaikiran Pai]

> Can I please get a review of this change to the jtreg failure handler that we use in the JDK? As noted in https://bugs.openjdk.org/browse/JDK-8374754 this change addresses the HTML rendering issues that are noticed in certain setups. The change here moves the inline javascript to a file of its own (generated as and when necessary).

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

  create the script and css files only if not already present

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Changes:
  - all: https://git.openjdk.org/jdk/pull/29106/files
  - new: https://git.openjdk.org/jdk/pull/29106/files/2ce710f1..dfda18c6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29106&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29106&range=00-01

  Stats: 6 lines in 1 file changed: 6 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/29106.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29106/head:pull/29106

PR: https://git.openjdk.org/jdk/pull/29106