fix(extra-natives/five): make track junction ids permanent

[TheGamerzs]

Goal of this PR

Make train junction ids permanent, not the relative index of the vector
Currently, the id will "change" if a junction is removed

How is this PR achieving the goal

Change junction vector to unmmapped_map
Creates a queue of unused ids

This PR applies to the following area(s)

FiveM

Successfully tested on

Game builds: 1607, 3407

Platforms: Windows

Checklist

• Code compiles and has been tested successfully.
• Code explains itself well and/or is documented.
• My commit message explains what the changes do and what they are for.
• No extra compilation warnings are added by these changes.

[prikolium-cfx]

Thank you for the contribution. Merged with some adjustments.