GAS: GameplayAttribute picker incorrectly also lists AttributeSets' non-attribute properties

Context: 

FGameplayAttribute's details customization lets designers pick any attribute property from any UAttributeSet class.

Problem:

This currently displays all properties of UAttributeSet classes. If a game project adds non-attribute properties (bools, FNames, etc) those are also pickable. These cannot represent gameplay attributes.

[Image Removed]

Suggested fix:

Only display FGameplayAttributeData and floating point numerical properties of UAttributeSets in the details customization for FGameplayAttribute.

• Define a UPROPERTY() bool MyNonAttribute; in any UAttributeSet
• Open a GameplayEffect blueprint
• Add a Modifiers entry
• Open the Attribute dropdown
• Observe: MyNonAttribute is selectable
• Expected: MyNonAttribute is not listed. Any non-FGameplayAttributeData and non-float should not be listed since they can't be attributes.