RFR: 8368877: Generate Jextract bindings for Kqueue

[Darragh Clarke]

This PR is based on #25546 , though it was suggested to split that PR into 2 for easier reviewing and to give better visibility in the git history.
This PR contains all the JExtract generated code that will be needed for converting Java's KQueue implementation to use Panama features instead of JNI. The actual updates to KQueue to make use of these files will come in the second PR.

The basic structure here has the different native structures and methods split into 3 different packages all preceded by
`src/java.base/macosx/classes/jdk/internal/ffi/generated/`
Included in each package is a file `package-info.java` which contains the script that was used to generate these files so that others can reproduce them in future.

The only modifications that have been made to the files post-generation are:
- Adding copyright headers
- Adding warning suppression for using restricted methods

Some further modifications to these files to cut down on code duplication and adding support for errno handling on the native calls will come in the 2nd PR alongside the KQueue changes mentioned.

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Commit messages:
 - added warning supression for restricted methods, fixed missing comma in copyright header
 - re-added the copyright headers
 - jextract generated code and the package-info.java files that describe how they were genereated

Changes: https://git.openjdk.org/jdk/pull/27590/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27590&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8368877
  Stats: 1351 lines in 11 files changed: 1351 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27590.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27590/head:pull/27590

PR: https://git.openjdk.org/jdk/pull/27590