[jdk11u-dev] RFR: 8272180: Upgrade JSZip from v3.6.0 to v3.7.1

[Jonathan Dowland]

This is an implementation of the fix described in JDK-8272180, which was backported to 11.0.13-oracle but which does not have a public patch.

I took jszip 3.7.1 from GitHub. The archive I downloaded was from <https://github.com/Stuk/jszip/archive/refs/tags/v3.7.1.tar.gz> and I calculate the sha1 sum to be `c5ba7227f1db44a2bd8e30e0cf7edbaf53ef4387` (note: calculated locally, I haven't yet convinced GitHub to show me a checksum for that archive that I can compare).

`jszip.js` and `jszip.min.js` are straight copies of the corresponding files from the path `dist/` in the jszip archive.

`src/jdk.javadoc/share/legal/jszip.md` is a copy of `jszip-3.7.1/LICENSE.markdown` with the following modifications:
 *  added ## JSZip v3.7.1 markdown header
 *  changed markdown headings to match the levels in the openjdk copy of the license (I.e., switched underline-style level 2 headings to prefix-style level 3 headings)
 *  added backticks to indicate pre-formatted text

Note that this update to `jszip.md` also resolves JDK-8272828 (Add correct licenses to jszip.md) for which there is also no public patch. There is no clear description of what the problem was with the license before, but jszip is dual licensed  MIT and GPL3, and prior to this, the 11u copy of the license only included MIT. I've preserved both licenses in this patch.

Initial testing: in a pet project (https://github.com/jmtd/wadc), I ran javadoc and inspected the output. Javadoc command:

    $JAVA_HOME/bin/javadoc -cp src/main/java --add-modules java.desktop -verbose  -d . org.redmars.wadc

Prior to patch: jszip 3.2.1 is bundled
After patch: jszip 3.7.1 is bundled

I also checked that the functionality jszip supports (client-side searching for keywords) was working. I got the same results before and after patch: immediate keyword suggestion/completion as I typed into the search box. Attempting to follow any of the links resulted in a broken link for me, however, with an additional "undefined/" included in the URI (file:///home/jon/git/doom/wadc.tmp2/undefined/org/redmars/wadc/EngineConfigDialog.html). I don't know the cause of this yet, so I can't attribute it to a problem in jszip (and if there is one, it's there already.)

I await GHA tier1 testing after raising this PR. I'll also check now which other javadoc-related tests are worth trying.

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Commit messages:
 - 8272180: Upgrade JSZip from v3.6.0 to v3.7.1

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/407/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=407&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272180
  Stats: 754 lines in 3 files changed: 656 ins; 26 del; 72 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/407.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/407/head:pull/407

PR: https://git.openjdk.java.net/jdk11u-dev/pull/407