New Script: Opengist

[jd-apprentice]

🛠️ Note:
We are meticulous about merging code into the main branch, so please understand that pull requests not meeting the project's standards may be rejected. It's never personal!
🎮 Note for game-related scripts: These have a lower likelihood of being merged.

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✍️ Description

I've added a tool named Opengist which is an open source alternative to GitHub Gist.
The installer includes install of the tool itself via the Golang binary and the creation of a systemd service to persist the app itself.

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🛠️ Type of Change

Please check the relevant options:

• New script (a fully functional and thoroughly tested script or set of scripts)

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✅ Prerequisites

The following steps must be completed for the pull request to be considered:

• Self-review performed (I have reviewed my code to ensure it follows established patterns and conventions.)
• Testing performed (I have thoroughly tested my changes and verified expected functionality.)
• Documentation updated (I have updated any relevant documentation)

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📋 Additional Information (optional)

Install step OK

App working