feat: add HotBarLayout

[theEvilReaper]

Proposed changes

The pull request introduces a HotBarLayout class to define and manage layouts for a player’s hotbar.

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

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• I have read the CONTRIBUTING.md
• I have added tests that prove my fix is effective or that my feature works
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[TheMeinerLP]

LGTM, covers this the only shared items oder general ?

[theEvilReaper]

In general it is designed to share items between players as the apply method takes a player as a parameter. However, it can also be limited to a single player,depending on the context.