Add support for visionOS

Except for SPM, which requires Swift 5.9. In addition we don't do any CI testing on visionOS simulators, since it seems to be a bit excessive.

Author: tsolomko

BitByteData.podspec

@@ -19,6 +19,7 @@ Pod::Spec.new do |s|
   s.osx.deployment_target = "10.13"
   s.tvos.deployment_target = "11.0"
   s.watchos.deployment_target = "4.0"
+  s.visionos.deployment_target = "1.0"
 
   s.swift_versions = ["5"]
 

BitByteData.xcodeproj/project.pbxproj

@@ -428,12 +428,13 @@
 				ONLY_ACTIVE_ARCH = YES;
 				OTHER_CODE_SIGN_FLAGS = "--deep";
 				SDKROOT = macosx;
-				SUPPORTED_PLATFORMS = "macosx watchsimulator iphonesimulator appletvsimulator watchos appletvos iphoneos";
+				SUPPORTED_PLATFORMS = "macosx watchsimulator iphonesimulator appletvsimulator watchos appletvos iphoneos xrsimulator xros";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
 				SWIFT_VERSION = 5.0;
 				TVOS_DEPLOYMENT_TARGET = 11.0;
 				VERSIONING_SYSTEM = "apple-generic";
 				WATCHOS_DEPLOYMENT_TARGET = 4.0;
+				XROS_DEPLOYMENT_TARGET = 1.0;
 			};
 			name = Debug;
 		};
@@ -478,12 +479,13 @@
 				MACOSX_DEPLOYMENT_TARGET = 10.13;
 				OTHER_CODE_SIGN_FLAGS = "--deep";
 				SDKROOT = macosx;
-				SUPPORTED_PLATFORMS = "macosx watchsimulator iphonesimulator appletvsimulator watchos appletvos iphoneos";
+				SUPPORTED_PLATFORMS = "macosx watchsimulator iphonesimulator appletvsimulator watchos appletvos iphoneos xrsimulator xros";
 				SWIFT_COMPILATION_MODE = wholemodule;
 				SWIFT_VERSION = 5.0;
 				TVOS_DEPLOYMENT_TARGET = 11.0;
 				VERSIONING_SYSTEM = "apple-generic";
 				WATCHOS_DEPLOYMENT_TARGET = 4.0;
+				XROS_DEPLOYMENT_TARGET = 1.0;
 			};
 			name = Release;
 		};

Package.swift

@@ -7,7 +7,9 @@ let package = Package(
         .macOS(.v10_13),
         .iOS(.v11),
         .tvOS(.v11),
-        .watchOS(.v4)
+        .watchOS(.v4),
+        // TODO: Enable after upgrading to Swift 5.9.
+        // .visionOS(.v1)
     ],
     products: [
         .library(