GH-1059: Add VALIDATE_WORKSPACE setting to XcodeProj (#1060)

In Xcode 12, if an app is linked against .framework files with multiple
architectures, it will generate an error about embedded framework
mismatches. Declaring this property (even with its default value of NO)
resolves the issue.

Author: dpogue

bin/templates/project/__TEMP__.xcodeproj/project.pbxproj

@@ -328,6 +328,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "__PROJECT_ID__";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				TARGETED_DEVICE_FAMILY = "1,2";
+				VALIDATE_WORKSPACE = NO;
 			};
 			name = Debug;
 		};
@@ -350,6 +351,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "__PROJECT_ID__";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				TARGETED_DEVICE_FAMILY = "1,2";
+				VALIDATE_WORKSPACE = NO;
 			};
 			name = Release;
 		};