RFR: JDK-8282214: Upgrade JQuery to version 3.6.0

[Hannes Wallnöfer]

This is a straightforward change to update the jQuery library used in javadoc to version 3.6.0. 

Both compressed and uncompressed versions of jQuery 3.6.0 were downloaded from https://jquery.com/download/ to replace the old version and all references in javadoc src and test code were updated to the new files. 

In addition to running javadoc tests I did a manual test of features that use jQuery (search and mobile navbar) in Firefox, Chrome and Safari and they all work as expected.

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Commit messages:
 - JDK-8282214: Upgrade JQuery to version 3.6.0

Changes: https://git.openjdk.java.net/jdk/pull/7694/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7694&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282214
  Stats: 172 lines in 8 files changed: 53 ins; 44 del; 75 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7694.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7694/head:pull/7694

PR: https://git.openjdk.java.net/jdk/pull/7694