Support Java 25

This MR addresses #1108568. It drops all code that relied on the Security Manager.

Changes:

  * Support Java 25 (Closes: #1108568):
    - d/p/javaws_change_java_policy.diff: drop patch, Security Manager is
      removed.
    - d/p/jdk-25-disable-policy-panel.patch: remove policy editor panel.
    - d/p/jdk-25-jlnp-classloader.patch: remove Security Manager and
      custom jar caching callback.
    - d/p/jdk-25-property-action.patch: replace GetPropertyAction with lambda.
    - d/p/jdk-25-remove-files.patch: exclude files that use removed APIs.
    - d/icedtea-netx.install: do not install javaws.policy.
    - d/rules: do not install policy editor launcher.
  * d/control: replace pkg-config with pkgconf.
  * d/icedtea-netx.lintian-overrides: add old-fsf-address-in-copyright-file
    override.

Testing:

• rebuild in sid chroot
• rebuild in sid chroot with Java 25 installed.
• Ran https://areo.info/mpf/
• Ran https://www.netphantom.com/jnlp/jnlp.html