LinuxContainer: Add ability to close stdin (#201)

This allows the user the ability to raise an EOF for the containers
stdin. Today there's no way to close stdin so something as simple as
"cat" and relying on EOF to move the process forward doesn't work

Sources/Containerization/VirtualMachineAgent.swift

@@ -14,6 +14,7 @@
 // limitations under the License.
 //===----------------------------------------------------------------------===//
 
+import ContainerizationError
 import ContainerizationOCI
 import Foundation
 
@@ -51,6 +52,7 @@ public protocol VirtualMachineAgent: Sendable {
     func resizeProcess(id: String, containerID: String?, columns: UInt32, rows: UInt32) async throws
     func waitProcess(id: String, containerID: String?, timeoutInSeconds: Int64?) async throws -> Int32
     func deleteProcess(id: String, containerID: String?) async throws
+    func closeProcessStdin(id: String, containerID: String?) async throws
 
     // Networking
     func up(name: String, mtu: UInt32?) async throws
@@ -59,3 +61,9 @@ public protocol VirtualMachineAgent: Sendable {
     func routeAddDefault(name: String, gateway: String) async throws
     func configureDNS(config: DNS, location: String) async throws
 }
+
+extension VirtualMachineAgent {
+    public func closeProcessStdin(id: String, containerID: String?) async throws {
+        throw ContainerizationError(.unsupported, message: "closeProcessStdin")
+    }
+}