Cleanup swift-testing migration (#1403)

* Cleanup swift-testing migration

* Remove FoundationEssentialsTests suite as it is incompatible with SwiftPM's build system

Author: jmschonfeld

Package.swift

@@ -99,10 +99,7 @@ let package = Package(
         // TestSupport (Internal)
         .target(
             name: "TestSupport",
-            dependencies: [
-                "FoundationEssentials",
-                "FoundationInternationalization",
-            ],
+            path: "Tests/TestSupport",
             cSettings: wasiLibcCSettings,
             swiftSettings: availabilityMacros + featureSettings
         ),

Sources/FoundationEssentials/JSON/JSONDecoder.swift

@@ -413,7 +413,7 @@ open class JSONDecoder {
 
             // Check for explicit BOM first, then check the first two bytes. Note that if there is a BOM, we have to create our string without it.
             // This isn't strictly part of the JSON spec but it's useful to do anyway.
-            let sourceEncoding : String._Encoding
+            let sourceEncoding : String.Encoding
             let bomLength : Int
             switch (byte0, byte1, byte2, byte3) {
             case (0, 0, 0xFE, 0xFF):

Sources/FoundationEssentials/String/String+Encoding.swift

@@ -50,13 +50,6 @@ extension String {
         public static let utf32LittleEndian = Encoding(rawValue: 0x9c000100)
     }
 
-    // This is a workaround for Clang importer's ambiguous lookup issue since
-    // - Swift doesn't allow typealias to nested type
-    // - Swift doesn't allow typealias to builtin types like String
-    // We therefore rename String.Encoding to String._Encoding for package
-    // internal use so we can use `String._Encoding` to disambiguate.
-    internal typealias _Encoding = Encoding
-
 #if FOUNDATION_FRAMEWORK
     public typealias EncodingConversionOptions = NSString.EncodingConversionOptions
     public typealias EnumerationOptions = NSString.EnumerationOptions

Sources/FoundationInternationalization/Formatting/Duration+TimeFormatStyle.swift

@@ -147,9 +147,6 @@ extension Duration {
         }
 
     }
-
-    // For testing purpose. See notes about String._Encoding
-    internal typealias _TimeFormatStyle = TimeFormatStyle
 }
 
 @available(macOS 13.0, iOS 16.0, tvOS 16.0, watchOS 9.0, *)

Sources/FoundationInternationalization/Formatting/Duration+UnitsFormatStyle.swift

@@ -495,9 +495,6 @@ extension Duration {
             Attributed(innerStyle: self)
         }
     }
-
-    // For testing purpose. See notes about String._Encoding
-    internal typealias _UnitsFormatStyle = UnitsFormatStyle
 }
 
 // `FormatStyle` static membership lookup