Use information of operand value to determine type for java locals

This PR uses the already existing information of the operand's value type to determine the type for java locals. Previously, most of the stack variables were of "unknown" type
.
Fixes #635

sootup.java.bytecode/src/main/java/sootup/java/bytecode/frontend/AsmMethodSource.java

@@ -291,9 +291,14 @@ void setStmt(@Nonnull AbstractInsnNode insn, @Nonnull Stmt stmt) {
 
   @Nonnull
   Local newStackLocal() {
+    return newStackLocal(UnknownType.getInstance());
+  }
+
+  @Nonnull
+  Local newStackLocal(Type type) {
     int idx = nextLocal++;
     JavaLocal l =
-        JavaJimple.newLocal("$stack" + idx, UnknownType.getInstance(), Collections.emptyList());
+            JavaJimple.newLocal("$stack" + idx, type, Collections.emptyList());
     locals.set(idx, l);
     return l;
   }