[XB] Prefix Content Permissions 1.0.0

Adds options to thread prefixes to restrict which user groups can view thread content and who can reply.

Features:​

• View Restrictions: Limit which user groups can view the content of threads with specific prefixes.
• Reply Restrictions: Control which user groups are allowed to reply to threads based on the prefix.
• Per-Prefix Settings: Configure permissions individually for each thread prefix.
• Multi-Prefix Integration: Fully compatible with the Multi Prefix add-on.
• Bypass Permission: Allow selected user groups to bypass prefix-based access restrictions.
• Advanced Caching: Uses caching to avoid N+1 query behaivor and minimal performance impact.

Use prefixes to create read-only topics, staff-only discussions, or controlled reply threads.

Screenshots:​