feat: gradle support (#10)

Switching to the ScaffoldIt Gradle Plugin adding:
- HytaleServer.jar via the official Hytale maven
- Monorepo support via `common {}` block
- Kotlin support via `useKotlin()` function
- Hot-reloading using DCEVM JVM and IDEA
- Automatic manifest in-place generation
- Automatic source path scaffolding
- Source-linked Devserver for zero jar
- Source-linked Asset Editor

.gitignore

@@ -36,4 +36,9 @@ build/
 .vscode/
 
 ### Mac OS ###
-.DS_Store
+.DS_Store
+
+### Gradle ###
+.gradle
+.kotlin
+devserver