move base project to 'core'

add build script for nms
add build script for core
add build script for project
move existing nms references to nms/v1_20_R1
add 1.19 and 1.20.2 compatibility

settings.gradle

@@ -22,4 +22,13 @@ pluginManagement {
         gradlePluginPortal()
     }
 }
-rootProject.name = 'Iris'
+rootProject.name = 'Iris'
+
+include(':core')
+include(
+        ':nms:v1_20_R2',
+        ':nms:v1_20_R1',
+        ':nms:v1_19_R3',
+        ':nms:v1_19_R2',
+        ':nms:v1_19_R1'
+)