Change synthetic accessor method names to "access$..."

As per discussion in https://youtrack.jetbrains.com/issue/KT-6870

compiler/testData/cli/jvm/signatureClash.kt

@@ -23,7 +23,7 @@ class SubTr : Tr {
 // Clashing synthetic accessors are only reported in compiler, IDE doesn't see them
 class C {
     private fun f() {}
-    fun `f$b$0`(c: C) {}
+    fun `access$f$0`(c: C) {}
 
     class Nested {
 
@@ -31,4 +31,4 @@ class C {
             C().f()
         }
     }
-}
+}