Add .editorconfig rules

Author: Goooler

.editorconfig

@@ -1,9 +1,14 @@
+root = true
+
 [*]
 charset = utf-8
 indent_size = 4
 indent_style = space
 insert_final_newline = true
 trim_trailing_whitespace = true
 
+[*.java]
+ij_java_use_single_class_imports = true
+
 [*.yml]
 indent_size = 2