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/ContainerizationExtras/AsyncLock.swift

@@ -16,6 +16,10 @@
 
 import Foundation
 
+/// `AsyncLock` provides a familiar locking API, with the main benefit being that it
+/// is safe to call async methods while holding the lock. This is primarily used in spots
+/// where an actor makes sense, but we may need to ensure we don't fall victim to actor
+/// reentrancy issues.
 public actor AsyncLock {
     private var busy = false
     private var queue: ArraySlice<CheckedContinuation<(), Never>> = []

Sources/ContainerizationExtras/Timeout.swift

@@ -16,7 +16,11 @@
 
 import Foundation
 
+/// `Timeout` contains helpers to run an operation and error out if
+/// the operation does not finish within a provided time.
 public struct Timeout {
+    /// Performs the passed in `operation` and throws a `CancellationError` if the operation
+    /// doesn't finish in the provided `seconds` amount.
     public static func run<T: Sendable>(
         seconds: UInt32,
         operation: @escaping @Sendable () async -> T