Source code documentation updates (#9)

This change adds documentation to quite a few existing public types that
didn't have a blurb before.

Additionally, this fixes a couple things that I think either didn't make
sense when going to document them:
- Rename ConnectionStream to VsockConnectionStream. This type only
functions for vsock connections.
- Deletes NsLock+Closure. This was not used anywhere.
- Rename ContainerizationOCI/Config.swift to ImageConfig.swift.

Signed-off-by: Danny Canter <danny_canter@apple.com>

Sources/Containerization/VsockConnectionStream.swift

@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025 Apple Inc. and the containerization project authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+#if os(macOS)
+import Virtualization
+#endif
+
+/// A stream of vsock connections.
+public final class VsockConnectionStream: NSObject, Sendable {
+    /// A stream of connections dialed from the remote.
+    public let connections: AsyncStream<FileHandle>
+    /// The port the connections are for.
+    public let port: UInt32
+
+    private let cont: AsyncStream<FileHandle>.Continuation
+
+    public init(port: UInt32) {
+        self.port = port
+        let (stream, continuation) = AsyncStream.makeStream(of: FileHandle.self)
+        self.connections = stream
+        self.cont = continuation
+    }
+
+    public func finish() {
+        self.cont.finish()
+    }
+}
+
+#if os(macOS)
+
+extension VsockConnectionStream: VZVirtioSocketListenerDelegate {
+    public func listener(
+        _: VZVirtioSocketListener, shouldAcceptNewConnection conn: VZVirtioSocketConnection,
+        from _: VZVirtioSocketDevice
+    ) -> Bool {
+        let fd = dup(conn.fileDescriptor)
+        conn.close()
+
+        cont.yield(FileHandle(fileDescriptor: fd, closeOnDealloc: false))
+        return true
+    }
+}
+
+#endif