Fix ExprDifference issues

[APickledWalrus]

Description

This PR aims to fix some issues, mainly with the initialization stage of ExprDifference.

There were multiple issues, but the main one (which is why #5331 had test failures) is that it does not properly compare known types. For example, if we had two types, string and number, the resolved class info is object (it's the shared superclass). Of course, this expression has handling for variables that allows object as a valid classinfo. However, this meant that the string and number difference would be accepted. This caused Skript to interpret the following line incorrectly in some cases:
difference between "%{_a}%" parsed as a number and "%{_b}%" parsed as a number
It should be interpreted as:
difference between ("%{_a}%" parsed as a number) and ("%{_b}%" parsed as a number)
However, because of the faulty checks, it would sometimes be interpreted as:
(difference between ("%{_a}%" parsed as a number) and "%{_b}%") parsed as a number

So, I've cleaned up the class, and the new logic is as follows:

If we have two known types:

• Attempt to convert them to each other - fail if no conversions can be made

If we have one known type:

• Attempt to convert object to the known type. I believe this will always succeed with new converters, but it also allows us to verify that the known type can actually have a difference operation performed on it

If we have no known types:

• Resolve during runtime when we know types

In the PR I mentioned above, ExprParse was sometimes registered before ExprDifference which is why this error occurred. It's not problematic right now because ExprDifference is registered before ExprParse (but we shouldn't depend on load order to prevent bugs!!)

Thorough review of the logic and additional testing is likely needed

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Target Minecraft Versions: Any
Requirements: None
Related Issues: none?

[kiip1]

Thanks :)

[AyhamAl-Ali]

Nice PR my associate ⚡

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