Update to 1.20 (#2276)

* Towards 1.20

* Init bukkit

* Update YAML to 2.0

* Fixes for 1.20 adapters

* Update obfuscated field names

* Remove getHandle workaround

* entityManager is obfuscated

* Update paperweight

* [ci-skip] Add 1.20 to modrinth task

---------

Co-authored-by: Phillipp Glanz <p.glanz@madfix.me>
Co-authored-by: SirYwell <hannesgreule@outlook.de>

worldedit-bukkit/adapters/adapter-1_20/build.gradle.kts

@@ -0,0 +1,17 @@
+import io.papermc.paperweight.userdev.PaperweightUserDependenciesExtension
+
+plugins {
+    java
+}
+
+applyPaperweightAdapterConfiguration()
+
+repositories {
+    gradlePluginPortal()
+}
+
+dependencies {
+    // https://repo.papermc.io/service/rest/repository/browse/maven-public/io/papermc/paper/dev-bundle/
+    the<PaperweightUserDependenciesExtension>().paperDevBundle("1.20-R0.1-20230609.070122-4")
+    compileOnly("io.papermc:paperlib")
+}