[Swift Export] Use ExportedBridge instead of ExportForCppRuntime

ExportedBridge annotation actually does what we need in Swift Export.
Unlike ExportForCppRuntime, it prevents symbol from DCE.

native/swift/sir-compiler-bridge/testData/smoke0/expected.kt

@@ -1,6 +1,6 @@
-import kotlin.native.internal.ExportForCppRuntime
+import kotlin.native.internal.ExportedBridge
 
-@ExportForCppRuntime("a_b_foo_bridge")
+@ExportedBridge("a_b_foo_bridge")
 public fun a_b_foo_bridge(param1: Int, param2: Long): Int {
     val result = a.b.foo(param1, param2)
     return result