RFR: 8337111: Bad HTML checker for generated documentation

[Nizar Benalla]

Doccheck's human-generated reports are great at previewing a "chessboard" of results. Giving reader a quick glimpse at the quality/health of the documentation. But these tests needed to be automated and they didn't easily translate to something that can be integrated into a CI.

This PR includes an HTML and internal link test on `api/java.base` and a BadChars and Doctype test on the entire generated documentation bundle.

Here is an example of the output after running all tests on `api/java.base`

Note: There is an active PR to fix the broken anchors left in `java.base` so this is not a blocker.



STDOUT:
STDERR:
test: test
Tidy found errors in the generated HTML
/Users/nizarbenalla/Work/jdk-repos/jdk1/build/macosx-aarch64/images/docs/api/java.base/java/lang/Class.html:323:87: Warning: <a> anchor "nest" already defined
Tidy output end.


api/java.base/java/util/concurrent/StructuredTaskScope.ShutdownOnFailure.html:245: id not found: api/java.base/java/util/concurrent/StructuredTaskScope.ShutdownOnFailure.html#TreeStructure
api/java.base/java/util/concurrent/StructuredTaskScope.ShutdownOnSuccess.html:242: id not found: api/java.base/java/util/concurrent/StructuredTaskScope.ShutdownOnSuccess.html#TreeStructure
api/java.base/java/lang/Class.html:323: name already declared: nest
api/java.base/java/lang/Module.html:291: id not found: api/java.base/java/lang/foreign/package-summary.html#restricted
api/java.base/java/lang/Module.html:434: id not found: api/java.base/java/lang/foreign/package-summary.html#restricted
api/java.base/java/lang/foreign/MemorySegment.html:725: id not found: api/java.base/java/lang/foreign/package-summary.html#restricted

Link Checker Report
Checked 3446 files.
Found 445059 references to 48205 anchors in 5770 files and 64 other URIs.
     1 duplicate ids
     3 missing ids

Hosts
    20 docs.oracle.com
     1 tools.ietf.org
     1 www.ietf.org
     1 jcp.org
     4 www.rfc-editor.org
     7 unicode.org
    10 www.unicode.org
    20 www.w3.org
Exception running test test: java.lang.Exception: One or more HTML checkers failed: [java.lang.RuntimeException: Tidy found errors in the generated HTML, java.lang.RuntimeException: LinkChecker encountered errors. Duplicate IDs: 1, Missing IDs: 3, Missing Files: 0, Bad Schemes: 0]
java.lang.Exception: One or more HTML checkers failed: [java.lang.RuntimeException: Tidy found errors in the generated HTML, java.lang.RuntimeException: LinkChecker encountered errors. Duplicate IDs: 1, Missing IDs: 3, Missing Files: 0, Bad Schemes: 0]
        at DocCheck.runCheckersSequentially(DocCheck.java:181)
        at DocCheck.test(DocCheck.java:166)
        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
        at java.base/java.lang.reflect.Method.invoke(Method.java:573)
        at toolbox.TestRunner.runTests(TestRunner.java:91)
        at toolbox.TestRunner.runTests(TestRunner.java:73)
        at DocCheck.main(DocCheck.java:128)
        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
        at java.base/java.lang.reflect.Method.invoke(Method.java:573)
        at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
        at java.base/java.lang.Thread.run(Thread.java:1576)

1 errors
java.lang.Exception: 1 errors found
        at toolbox.TestRunner.runTests(TestRunner.java:119)
        at toolbox.TestRunner.runTests(TestRunner.java:73)
        at DocCheck.main(DocCheck.java:128)
        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
        at java.base/java.lang.reflect.Method.invoke(Method.java:573)
        at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
        at java.base/java.lang.Thread.run(Thread.java:1576)

JavaTest Message: Test threw exception: java.lang.Exception: 1 errors found
JavaTest Message: shutting down test

-------------

Commit messages:
 - Convert parts of doccheck into tests

Changes: https://git.openjdk.org/jdk/pull/21879/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21879&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8337111
  Stats: 2009 lines in 13 files changed: 2009 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21879.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21879/head:pull/21879

PR: https://git.openjdk.org/jdk/pull/21879