[Fixes #14117] Fixes option to configure the default permissions for registered members and add for annonymous default

[sijandh35]

Fixes #14117

Checklist

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[gemini-code-assist]

Code Review

This pull request introduces a compact permissions system for default groups, deprecating the legacy boolean settings for anonymous view and download permissions. It implements the DEFAULT_ANONYMOUS_PERMISSIONS and DEFAULT_REGISTERED_MEMBERS_PERMISSIONS settings and adds a new DefaultSpecialGroupsPermissionsHandler to automate permission assignment during resource creation. The changes span security handlers, models, and the Geoserver manager to ensure integration and backward compatibility, supported by new unit tests. I have no feedback to provide.