Update UnrealEngine.gitignore

[MountainKing123]

Edited Unreal Engine gitignore to also ignore Intermediate data in the Plugins directory, so it ignores deeper nested intermediate data, like with Epic's Game Features plugin e.g. Plugins/GameFeatures/MyGameFeature/Intermediate.

Links to documentation supporting these rule changes:

The applied glob pattern: https://github.com/git/git/blob/3ee1e0fe11e2eb617170d0487fccfffc67f2b82b/Documentation/glossary-content.txt#L358-L383

Unreal Engine's Game Feature plugin docs. with the required directory structure which is currently not ignored accordingly in the template: https://dev.epicgames.com/documentation/fr-fr/unreal-engine/game-features-and-modular-gameplay-in-unreal-engine?application_version=5.3