Added Discord Chat Event Listener to Queue

[beanbeanjuice]

Pull Request

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Description

The event listener originally immediately attempted to get added to the jda. However, making the Discord bot asynchronous will sometimes break this as the jda will sometimes be null.

Fixes #144

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Type of Change

• [ ] Bug Fix (Small Non-Code Breaking Issue)
• [x] Bug Fix (Critical Code Breaking Issue)
• [ ] Feature (Something New Added to the Code)
• [ ] Improvement (Improving An Existing Section of Code)
• [ ] Documentation Update
• [ ] Security Vulnerability

Changes

• [x] Internal Code
• [ ] Documentation
• [ ] Other: _____

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Test Configuration

• Hardware:
  • CPU: AMD Ryzen 7 5800x3D
  • GPU: Nvidia RTX 3080
  • RAM: 32 GB DDR4
• JDK: Java OpenJDK 17

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Checklist

• [x] This pull request has been linked to the appropriate issue on GitHub. (Use the development section on the right.)
• [x] The code follows the style guidelines.
• [x] A self-review of the code was performed on GitHub.
• [x] Appropriate comments and javadocs were added in your code.
• [x] Appropriate changes have been made to the documentation.
• [x] Appropriate changes have been made to the README.md file.
• [x] No warnings are produced when the code is run.
• [x] Appropriate tests exist for this pull request.
• [x] New and existing Maven CI tests have passed.
• [x] The pull request is properly merging into the correct branch.
• [x] All existing local code has been pushed to the GitHub repository.
• [x] Changes have been documented in the current draft ProxyChat Releases update.