feat: global --source-root — index/mv/check/fix one subtree; deterministic Java FQN resolution in monorepos with duplicate packages (guava vs android/guava); move mv_reject to output.rs

tests/java/monorepo/android/guava/src/com/example/Primitives.java

@@ -0,0 +1,3 @@
+package com.example;
+
+public class Primitives {}

tests/java/monorepo/android/guava/src/com/example/app/App.java

@@ -0,0 +1,5 @@
+package com.example.app;
+
+import com.example.Primitives;
+
+public class App { Primitives p; }

tests/java/monorepo/guava/src/com/example/Primitives.java

@@ -0,0 +1,3 @@
+package com.example;
+
+public class Primitives {}

tests/java/monorepo/guava/src/com/example/app/App.java

@@ -0,0 +1,5 @@
+package com.example.app;
+
+import com.example.Primitives;
+
+public class App { Primitives p; }