Feature/get shared item

[Cocodrulo]

Description

This pull request introduces a new helper function to the shared codebase to simplify access to shared data. The main change is the addition of a generic GetShared function, making it easier and safer to retrieve shared data from various shared namespaces.

Helper function addition:

• Added the GetShared function to shared/main.lua, allowing retrieval of shared data from specified shared namespaces with safe navigation.

Checklist

• I have personally loaded this code into an updated qbcore project and checked all of its functionality.
• My code fits the style guidelines.
• My PR fits the contribution guidelines.