[embedded] Port Swift.String to embedded Swift

test/embedded/stdlib-strings-datatables.swift

@@ -0,0 +1,25 @@
+// Test String operations that require unicode data tables. This is not an executable test yet, because the data tables
+// are not available for linking yet.
+
+// RUN: %target-swift-frontend -emit-ir %s -enable-experimental-feature Embedded
+
+// REQUIRES: swift_in_compiler
+// REQUIRES: optimized_stdlib
+// REQUIRES: OS=macosx || OS=linux-gnu
+
+public func test1() {
+  let string = "string"
+  let other = "other"
+  let appended = string + other
+  _ = appended
+
+  let _ = "aa" == "bb"
+  let dict: [String:Int] = [:]
+  _ = dict
+
+  let _ = "aaa".uppercased()
+
+  let space: Character = " "
+  let split = appended.split(separator: space)
+  _ = split
+}