Add new locking feature to threads/posts

[Xeno852]

Implements User Story 5 #52

Resolves #XXXX

Summary

• Added lock button component and locked status display on the topic frontend.
• Added locked field to the Topic object in the database.
• Edited user privileges so only topic owners, administrators, and moderators can lock or unlock a topic.
• Added API endpoints for locking and unlocking topics.
• Set up backend event handling for lock button clicks (event listeners).
• Added controller functions to update the locked field given appropriate permissions.

Motivation

The ability to lock topics is essential for forum moderation and organization:

• As a topic owner, I can prevent further replies when I no longer require assistance or when a conversation is concluded, reducing noise.
• As a moderator or administrator, I can lock topics to prevent off-topic discussions or when forum rules are violated.

Implementing this feature enhances NodeBB's capabilities as a forum tool by providing users and staff with greater control over discussions.

Changes Made

• No existing functionalities were edited or removed.
• Added new locking functionality, including frontend components and backend logic.
• Made the locking functionality more obvious and user friendly by making it a button.

Testing INCOMPLETE

Visual Testing

• Created a new topic, verified that I could mark the new topic as unlocked

INCOMPLETE

Automated Testing

• NONE