Remove old plugin support and migrate to Piston (non-FAWE)

worldedit-core/build.gradle.kts

@@ -29,6 +29,7 @@ dependencies {
     "compile"("org.slf4j:slf4j-api:1.7.26")
     "compile"("it.unimi.dsi:fastutil:8.2.1")
     "compile"("com.googlecode.json-simple:json-simple:1.1.1") { isTransitive = false }
+
     "compileOnly"(project(":worldedit-libs:core:ap"))
     "annotationProcessor"(project(":worldedit-libs:core:ap"))
     // ensure this is on the classpath for the AP