Update WorkspaceSettings - use legacy build system

Since migrating to CocoaPods, we had to pod install to compile local changes - using legacy build system works around that.

playground/ios/playground.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>BuildSystemType</key>
+	<string>Original</string>
+	<key>PreviewsEnabled</key>
+	<false/>
+</dict>
+</plist>