Fix for Linux remote script debugging hang (#2213)

* Fix for Linux remote debugging hang bug.

* Removing dependency in PSReadLine on new engine helper API since it needs to be compatible with V3.

test/powershell/Host/HostUtilities.Tests.ps1

@@ -0,0 +1,70 @@
+Describe "InvokeOnRunspace method argument error handling" -tags "Feature" {
+
+    BeforeAll {
+        $command = [System.Management.Automation.PSCommand]::new()
+        $localRunspace = $host.Runspace
+    }
+
+    It "Null argument exception should be thrown for null PSCommand argument" {
+
+        try
+        {
+            [System.Management.Automation.HostUtilities]::InvokeOnRunspace($null, $localRunspace)
+            throw "InvokeOnRunspace method did not throw expected PSArgumentNullException exception"
+        }
+        catch
+        {
+            $_.FullyQualifiedErrorId | Should Be "PSArgumentNullException"
+        }
+    }
+
+    It "Null argument exception should be thrown for null Runspace argument" {
+
+        try
+        {
+            [System.Management.Automation.HostUtilities]::InvokeOnRunspace($command, $null)
+            throw "InvokeOnRunspace method did not throw expected PSArgumentNullException exception"
+        }
+        catch
+        {
+            $_.FullyQualifiedErrorId | Should Be "PSArgumentNullException"
+        }
+    }
+}
+
+Describe "InvokeOnRunspace method as nested command" -tags "Feature" {
+
+    It "Method should successfully invoke command as nested on busy runspace" {
+
+        $command = [System.Management.Automation.PSCommand]::new()
+        $command.AddScript('"Hello!"')
+        $currentRunspace = $host.Runspace
+
+        $results = [System.Management.Automation.HostUtilities]::InvokeOnRunspace($command, $currentRunspace)
+
+        $results[0] | Should Be "Hello!"
+    }
+}
+
+Describe "InvokeOnRunspace method on remote runspace" -tags "Feature" {
+    
+    BeforeAll {
+        $wc = [System.Management.Automation.Runspaces.WSManConnectionInfo]::new()
+        $remoteRunspace = [runspacefactory]::CreateRunspace($host, $wc)
+        $remoteRunspace.Open()
+    }
+
+    AfterAll {
+        $remoteRunspace.Dispose();
+    }
+
+    It "Method should successfully invoke command on remote runspace" {
+
+        $command = [System.Management.Automation.PSCommand]::new()
+        $command.AddScript('"Hello!"')
+
+        $results = [System.Management.Automation.HostUtilities]::InvokeOnRunspace($command, $remoteRunspace)
+
+        $results[0] | Should Be "Hello!"
+    }
+}