Disambiguate the names and trap labels of backing fields of extension properties

java/ql/test/kotlin/library-tests/clashing-extension-fields/test.expected

@@ -0,0 +1,9 @@
+|  |
+| <clinit> |
+| A |
+| B |
+| get |
+| getX |
+| invoke |
+| x$delegatepackagename$$subpackagename$$A |
+| x$delegatepackagename$$subpackagename$$B |

java/ql/test/kotlin/library-tests/clashing-extension-fields/test.kt

@@ -0,0 +1,7 @@
+package packagename.subpackagename
+
+public class A { }
+public class B { }
+
+val A.x : String by lazy { "HelloA" }
+val B.x : String by lazy { "HelloB" }

java/ql/test/kotlin/library-tests/clashing-extension-fields/test.ql

@@ -0,0 +1,5 @@
+import java
+
+from Class c
+where c.fromSource()
+select c.getAMember().toString()