add parsing of labels

[Aske-Rosted]

This pull request allows for proper parsing of labels in the dataset class, such that the new "Direction" (

graphnet/src/graphnet/training/labels.py

Line 29 in 9530955

class Direction(Label):

) can be instantiated correctly from a dataset config by adding the following.

labels: direction: arguments: azimuth_key: azimuth zenith_key: zenith class_name: Direction

to a .yml config file.

[RasmusOrsoe]

@Aske-Rosted If you update this branch with the latest from main, the tests should pass. #656

[RasmusOrsoe]

@Aske-Rosted thank you for adding this.

[RasmusOrsoe]

@Aske-Rosted please update this with latest from main before you merge