Make Array.size() a function instead of a property

Also add a deprecated extension property to help migration. This is done to
unify getting size of arrays and collections

compiler/testData/diagnostics/tests/kt310.kt

@@ -1,3 +1,3 @@
-fun f(c: Array<Int>): Int {
-    return c.<!FUNCTION_EXPECTED!>size<!>()
+fun f(c: String): Int {
+    return c.<!FUNCTION_EXPECTED!>length<!>()
 }