feat(580): Scripting Support in Backend

[SoulKa]

Changes

• Add ScriptingService that runs user defined scripts in a limited context (supports modifying variables etc.)
• Run script before and after request sending if exists
• Add methods to load and save script in requests

What's still missing is:

• synchronizing modified variables back to frontend
• saving script content when request is switched
• script editor

Testing

• Added automated tests
• Used a script to modify a variable before sending and see if it was used in request

Checklist

• Issue has been linked to this PR
• Code has been reviewed by person creating the PR
• Automated tests have been written, if possible
• Manual testing has been performed
• Documentation has been updated, if necessary
• Changes have been reviewed by second person