Gameplay Tags: Consider tag redirects in RequestGameplayTag()

Users can obtain a FGameplayTag reference by calling FGameplayTag::RequestGameplayTag(TagName) passing in a path like MyCategory.MyGameplayTag.

Users can rename INI-defined tags in the editor via the Gameplay Tag Manager in project settings by right clicking a tag and choosing Rename. This results in a +GameplayTagRedirects entry in DefaultGameplayTags.ini. Thanks to this redirect assets will properly use the new gameplay tag path.

Code that still calls FGameplayTag::RequestGameplayTag() with the old tag name will fail to resolve the renamed tag. FGameplayTag::RequestGameplayTag() should take into account tag redirects so that renaming a gameplay tag in the editor doesn't result in code being unable to resolve it.

Repro steps:

• Create a gameplay tag in editor Test.MyTag
• In code, like AMyActor::BeginPlay(), resolve the tag with FGameplayTag::RequestGameplayTag("Test.MyTag");
• Print out the tag's ToString() and when starting play, observe that it succeeds.
• In editor, rename the tag to Test.MyRenamedTag
• Observe: When starting play, it fails to print the renamed tag's name but "None" instead. This is because the gameplay tag could not be resolved.
• Expected: It should print the renamed tag's name, RequestGameplayTag() should resolve to the renamed tag.