handleModrinthProjects Cleanroom support (#4351)

Co-authored-by: etzabo <ethan@etzabo.com>
Co-authored-by: Geoff Bourne <988985+itzg@users.noreply.github.com>

scripts/start-setupModpack

@@ -313,6 +313,8 @@ function handleModrinthProjects() {
       loader=${HYBRIDTYPE}
     elif isFamily VANILLA; then
       loader=datapack
+    elif isFamily FORGE; then
+      loader=forge
     else
       loader="${TYPE,,}"
     fi