Loom 1.8+ does not generate a build\datagen directory, causing the 'Run Datagen' run configuration to be broken

[dicedpixels]

Loom 1.8+ no longer generates a build\datagen directory. This leaves 'Run Datagen' run configuration broken till you manually create that directory.

This behavior is not seen in Loom 1.7.

Steps to reproduce:

• Generate a fresh template project from https://fabricmc.net/develop/template/ with 'Data Generation' enabled.
• Open the project, wait for Gradle sync to finish, then restart the IDE (in my case IDEA) to load the run configurations.
• The 'Run Datagen' configuration will appear broken.