Incorrectly named methods for adding multiple values to `RunSourceSets`

[XFactHD]

The methods for adding multiple source sets via var-arg or Iterable to a RunSourceSets are incorrectly called add() instead of addAll(). This causes a regression from previous versions where the modSources property was a ListProperty.
https://github.com/neoforged/NeoGradle/blob/9c0462681075cf3838be6f5eafff8c9ed0f82837/dsl/common/src/main/groovy/net/neoforged/gradle/dsl/common/runs/run/RunSourceSets.groovy#L26-L40 https://github.com/neoforged/NeoGradle/blob/9c0462681075cf3838be6f5eafff8c9ed0f82837/dsl/common/src/main/groovy/net/neoforged/gradle/dsl/common/runs/run/RunSourceSets.groovy#L74-L88