[SK2] Add Configuration.with(storeKitVersion:) to select the versio…

…n of StoreKit to use (#3487)

This PR introduces a new configuration option to select the StoreKit
version to use.

It supersedes the deprecated `.with(usesStoreKit2IfAvailable: true)` and
the internal `usesStoreKit2JWS` configuration options.

Uses JWS tokens instead of SK1 receipts when in StoreKit 2 mode where
applicable.

Example usage:
```swift
Purchases.configure(
            with: .builder(withAPIKey: apiKey)
                .with(storeKitVersion: .storeKit2)
                .build()
```

RevenueCat.xcodeproj/project.pbxproj

@@ -206,9 +206,9 @@
 		4D6ABB0E2AF13FB100BB2A08 /* StoreEnvironment.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D6ABB0D2AF13FB100BB2A08 /* StoreEnvironment.swift */; };
 		4D6ABB102AF13FBD00BB2A08 /* SK2AppTransaction.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D6ABB0F2AF13FBD00BB2A08 /* SK2AppTransaction.swift */; };
 		4D72E8622B221EA600BF9EFE /* StoreEnvironmentTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4D24EF3F2B04EA6000E586D2 /* StoreEnvironmentTests.swift */; };
+		4DBC30962B1DFA97001D33C7 /* StoreKitVersion.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4DBC30952B1DFA97001D33C7 /* StoreKitVersion.swift */; };
 		4DBF1F362B4D572400D52354 /* LocalReceiptFetcher.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4DBF1F352B4D572400D52354 /* LocalReceiptFetcher.swift */; };
 		4DBF1F372B4D572400D52354 /* LocalReceiptFetcher.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4DBF1F352B4D572400D52354 /* LocalReceiptFetcher.swift */; };
-		4DBC30962B1DFA97001D33C7 /* StoreKitVersion.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4DBC30952B1DFA97001D33C7 /* StoreKitVersion.swift */; };
 		4DC546272AD44BBE005CDB35 /* EncodedAppleReceipt.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4DC546262AD44BBE005CDB35 /* EncodedAppleReceipt.swift */; };
 		4F0201C42A13C85500091612 /* Assertions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4F0201C32A13C85500091612 /* Assertions.swift */; };
 		4F05876F2A5DE03F00E9A834 /* PaywallDataTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4F05876E2A5DE03F00E9A834 /* PaywallDataTests.swift */; };
@@ -1001,8 +1001,8 @@
 		4D6ABB0B2AF13F9400BB2A08 /* StoreKit2Receipt.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = StoreKit2Receipt.swift; sourceTree = "<group>"; };
 		4D6ABB0D2AF13FB100BB2A08 /* StoreEnvironment.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = StoreEnvironment.swift; sourceTree = "<group>"; };
 		4D6ABB0F2AF13FBD00BB2A08 /* SK2AppTransaction.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SK2AppTransaction.swift; sourceTree = "<group>"; };
-		4DBF1F352B4D572400D52354 /* LocalReceiptFetcher.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LocalReceiptFetcher.swift; sourceTree = "<group>"; };
 		4DBC30952B1DFA97001D33C7 /* StoreKitVersion.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StoreKitVersion.swift; sourceTree = "<group>"; };
+		4DBF1F352B4D572400D52354 /* LocalReceiptFetcher.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LocalReceiptFetcher.swift; sourceTree = "<group>"; };
 		4DC546262AD44BBE005CDB35 /* EncodedAppleReceipt.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = EncodedAppleReceipt.swift; sourceTree = "<group>"; };
 		4F0201C32A13C85500091612 /* Assertions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Assertions.swift; sourceTree = "<group>"; };
 		4F05876E2A5DE03F00E9A834 /* PaywallDataTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PaywallDataTests.swift; sourceTree = "<group>"; };