ExprTestPlayer + Comparator Update

[Absolutionism]

Description

This PR aims to add a test-player to the testing environment allowing for easier usage of needing a player for a test. Having this expression makes all usages be the same, so if and when, for whatever reason, we can not get Notch as an OfflinePlayer, can just change the field within the class.

Also adds an OfflinePlayer to UUID comparator, and updates the OfflinePlayer to String comparator, if the String was in the form of a UUID

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Target Minecraft Versions: any Requirements: none Related Issues: none

[Burbulinis]

You could add tests for the OfflinePlayer and UUID comparator in the ExprUUID.sk file

[Absolutionism]

Seems 1.20.4 and 1.20.6 are not a fan of the UUID version.