[ruby/prism] Rename Java package to org.ruby_lang.prism

This moves all of the non-JRuby Java code from the org.prism
package to the org.ruby_lang.prism package (corresponding to the
ruby-lang.org domain and prism project).

ruby/prism@80b7402f8b

Author: headius

prism/templates/template.rb

@@ -724,9 +724,9 @@ def locals
       "javascript/src/deserialize.js",
       "javascript/src/nodes.js",
       "javascript/src/visitor.js",
-      "java/org/prism/Loader.java",
-      "java/org/prism/Nodes.java",
-      "java/org/prism/AbstractNodeVisitor.java",
+      "java/org/ruby_lang/prism/Loader.java",
+      "java/org/ruby_lang/prism/Nodes.java",
+      "java/org/ruby_lang/prism/AbstractNodeVisitor.java",
       "lib/prism/compiler.rb",
       "lib/prism/dispatcher.rb",
       "lib/prism/dot_visitor.rb",