Tag Change Delegates

[Packetdancer]

This is an actual feature addition, separate from the cleanup PR, and adds several things:

• An OnActiveTagsChanged delegate, called when the active tags change at all.
• The ability to add targeted delegates, which will only be called when changes to tags match a specific filter.
• A WaitForGameplayTagChange ability task, powered by the above.

The second of those is also necessary to (properly) create a GMCAbilitySystem equivalent to GAS's ability to map tag filters to blueprint properties and have them automatically updated, which is kinda useful in general and very useful in animation blueprints specifically.

[Packetdancer]

I just went ahead and added the rest of #22 to this pull request.

There's now an FGMCGameplayElementTagPropertyMap which can map changes to the active tags to a blueprint property automatically, utilizing the filtered tag change delegates. Each individual mapping supports taking a gameplay tag container and mapping it to one property on the blueprint which owns the property map.

• Bool properties will be set to true or false depending on whether the active tags contain any of the tags in the gameplay tag container.
• Int, Float, and Double properties will be set to the number of active tags matching the tags in the gameplay tag container.

Tag matches are not exact, so you can map a parent tag and it will match the children.

This also adds an UGMCAbilityAnimInstance animation blueprint parent, which automatically populates a convenience reference to the owning actor's ability component, and has a property map built in.

Additionally, because there's no way to have an appropriate detail widget for this otherwise, there's now a GMCAbiltySystemEditor module which contains a property detail customization to allow editing the property mapping.

[reznok]

Pax this is insanely impressive. Thank you.

[LeoFabre]

This is amazing. Thanks a huge ton ! 😍 Can't wait to use this