VSCode: Add Shellscript Syntax highlighting for *.func files

[andygrunwald]

✍️ Description

*.func files won't be recognized as shellscript files.
This Pull Request adds configuration for VSCode to add proper syntax highlighting for *.func files.

✅ Prerequisites

• 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.)

🛠️ Type of Change

• [] Bug fix (non-breaking change that resolves an issue)
• New feature (non-breaking change that adds functionality)
• [] Breaking change (fix or feature that would cause existing functionality to change unexpectedly)
• [] New script (a fully functional and thoroughly tested script or set of scripts)

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📋 Additional Information (optional)

None