Common stdlib

- adds actual matching expect declarations
- removes duplicates
- rewrite collections
- add MPP and experimental compiler options

backend.native/tests/runtime/text/string_builder0.kt

@@ -170,10 +170,10 @@ fun testReverse() {
     assertTrue(builder === builder.reverse())
     assertEquals(builder, "654321")
 
-    builder.length = 1
+    builder.setLength(1)
     assertEquals(builder, "6")
 
-    builder.length = 0
+    builder.setLength(0)
     assertEquals(builder, "")
 
     var str: String = "a"
@@ -261,7 +261,7 @@ fun testBasic() {
     assertEquals(19, sb.length)
     assertEquals("1, true12345678null", sb.toString())
 
-    sb.length = 0
+    sb.setLength(0)
     assertEquals(0, sb.length)
     assertEquals("", sb.toString())
 }

backend.native/tests/stdlib_external/text/harmony_regex/PatternTest2.kt

@@ -965,7 +965,7 @@ class PatternTest2 {
         assertEquals(4, result!!.range.start)
 
         // modify text
-        text.length = 0
+        text.setLength(0)
         text.append("Text have been changed.")
 
         assertNull(regex.find(text))