Add Helper Methods for Scene Loading

[EvroDeveloper]

• Added LoadLevel methods, supports string barcodes or Crate References, with optional overloads for specific loading scenes.
• Added FadeLoadLevel methods, same parameters as all the Load level methods, but will trigger a short fadeout to black before loading the level (just like patch 3). Includes an extra bool parameter to specify if it should fade with the fast variant.

Also added the two types of LoadFade barcodes to CommonBarcodes

(this was all done on a chromebook via vscode, there may be errors and stuff)

[HAHOOS]

Method has errors, fixed:

private static System.Collections.IEnumerator FadeIntoLevel(Barcode level, Barcode loadScene, bool fastFade = false)
{
    if (fastFade)
    {
        SpawnCrate(CommonBarcodes.Misc.LoadFadeFast, Vector3.zero);
        yield return new WaitForSeconds(0.5f);
    }
    else
    {
        SpawnCrate(CommonBarcodes.Misc.LoadFade, Vector3.zero);
        yield return new WaitForSeconds(2);
    }
    LoadLevel(level.ID, loadScene.ID);
}

[EvroDeveloper]

Thanks, should be fixed now!

[HAHOOS]

Tested (pressed the "Load Random Level" in the DefaultMenu which was updated to use FadeLoadLevel. I do not believe it needs more testing than that as most of the code is the same), seems to work just fine

[adamd3v]

Does this feature work on Quest? I know that it may work fine on PCVR due to the WaitForSeconds yield instruction. On Quest, it may just skip the yield instruction and immediately run the level loading code.

[HAHOOS]

Tested on Quest, the WaitForSeconds yield instruction is not being skipped

[adamd3v]

Fantastic, I'll merge this soon! I'll have to examine the merge conflicts though and test the functionality out.

[EvroDeveloper]

I believe I fixed the merge conflicts by merging from upstream and fixing the conflicts. Still new to contributing on GitHub so let me know if there is anything I missed, but it should hopefully be good now.