[6.0] Fix checksum computation for Swift SDK bundles (#7749)

Cherry-pick of
#7748.

**Explanation**: This feature [was specified in the corresponding
proposal for Swift
SDKs](https://github.com/swiftlang/swift-evolution/blob/main/proposals/0387-cross-compilation-destinations.md#swift-sdk-installation-and-configuration):

> For Swift SDKs installed from remote URLs an additional `--checksum`
option is required, through which users of a Swift SDK can specify a
checksum provided by a publisher of the SDK. The latter can produce a
checksum by running `swift package compute-checksum` command (introduced
in
[SE-0272](https://github.com/swiftlang/swift-evolution/blob/main/proposals/0272-swiftpm-binary-dependencies.md))
with the Swift SDK bundle archive as an argument.

Currently, `swift package compute-checksum` is unable to handle
`.tar.gz` bundles, which is a commonly used format for Swift SDKs. We're
fixing that here by adding correct and unified handling for archive
extensions.

This change is isolated to the `swift package compute-checksum`
subcommand. The `--checksum` option is added in a subsequent PR:
#7722.

**Scope**: Isolated to `swift package compute-checksum` subcommand.
**Risk**: Low, no existing behavior is 
**Testing**: Automated test cases modified/added and passing in a
subsequent PR:
#7723
**Issue**: rdar://130590711
**Reviewer**: @bnbarham

Author: MaxDesiatov

Sources/Basics/Archiver/Archiver.swift

@@ -95,4 +95,8 @@ extension Archiver {
             self.validate(path: path, completion: { continuation.resume(with: $0) })
         }
     }
+
+    package func isFileSupported(_ lastPathComponent: String) -> Bool {
+        self.supportedExtensions.contains(where: { lastPathComponent.hasSuffix($0) })
+    }
 }

Sources/Commands/PackageCommands/ComputeChecksum.swift

@@ -28,17 +28,10 @@ struct ComputeChecksum: SwiftCommand {
     var path: AbsolutePath
 
     func run(_ swiftCommandState: SwiftCommandState) throws {
-        let binaryArtifactsManager = try Workspace.BinaryArtifactsManager(
-            fileSystem: swiftCommandState.fileSystem,
-            authorizationProvider: swiftCommandState.getAuthorizationProvider(),
-            hostToolchain: swiftCommandState.getHostToolchain(),
-            checksumAlgorithm: SHA256(),
-            cachePath: .none,
-            customHTTPClient: .none,
-            customArchiver: .none,
-            delegate: .none
+        let checksum = try Workspace.BinaryArtifactsManager.checksum(
+            forBinaryArtifactAt: self.path,
+            fileSystem: swiftCommandState.fileSystem
         )
-        let checksum = try binaryArtifactsManager.checksum(forBinaryArtifactAt: path)
         print(checksum)
     }
 }

Sources/Workspace/Workspace+BinaryArtifacts.swift

@@ -18,7 +18,7 @@ import SPMBuildCore
 
 import struct TSCBasic.ByteString
 import protocol TSCBasic.HashAlgorithm
-
+import struct TSCBasic.SHA256
 import enum TSCUtility.Diagnostics
 
 extension Workspace {
@@ -537,20 +537,35 @@ extension Workspace {
             return result.get()
         }
 
-        public func checksum(forBinaryArtifactAt path: AbsolutePath) throws -> String {
+        package static func checksum(
+            forBinaryArtifactAt path: AbsolutePath,
+            hashAlgorithm: HashAlgorithm = SHA256(),
+            archiver: (any Archiver)? = nil,
+            fileSystem: any FileSystem
+        ) throws -> String {
+            let archiver = archiver ?? UniversalArchiver(fileSystem)
             // Validate the path has a supported extension.
-            guard let pathExtension = path.extension, self.archiver.supportedExtensions.contains(pathExtension) else {
-                let supportedExtensionList = self.archiver.supportedExtensions.joined(separator: ", ")
+            guard let lastPathComponent = path.components.last, archiver.isFileSupported(lastPathComponent) else {
+                let supportedExtensionList = archiver.supportedExtensions.joined(separator: ", ")
                 throw StringError("unexpected file type; supported extensions are: \(supportedExtensionList)")
             }
 
             // Ensure that the path with the accepted extension is a file.
-            guard self.fileSystem.isFile(path) else {
+            guard fileSystem.isFile(path) else {
                 throw StringError("file not found at path: \(path.pathString)")
             }
 
-            let contents = try self.fileSystem.readFileContents(path)
-            return self.checksumAlgorithm.hash(contents).hexadecimalRepresentation
+            let contents = try fileSystem.readFileContents(path)
+            return hashAlgorithm.hash(contents).hexadecimalRepresentation
+        }
+
+        public func checksum(forBinaryArtifactAt path: AbsolutePath) throws -> String {
+            try Self.checksum(
+                forBinaryArtifactAt: path,
+                hashAlgorithm: self.checksumAlgorithm,
+                archiver: self.archiver,
+                fileSystem: self.fileSystem
+            )
         }
 
         public func cancel(deadline: DispatchTime) throws {