Ability to Preview Crates

[varunbln]

Please make sure your issue complies with these guidelines:

• • [x] Use same formatting
• • [x] Changes must have been tested on PMMP.
• • [x] Unless it is a minor code modification, you must use an IDE.
• • [x] Have a detailed title (i.e "Fix Crate items don't appear in inventory")

What does the PR change?

This PR aims to add the ability to preview the items within a crate. The RouletteTask has been modified to loop through all possible drops endlessly without giving the player an item, until the player closes the menu.

Testing Environment

• PocketMine-MP: 3.11.5
• PHP: 7.2
• Server OS: Windows 10

Extra Information

The InvMenu virion is used.

[Aericio]

@DaPigGuy change your review smh