Provide a bit more accurate "reason" for debug stop.

It turns out that when the debugger stops at a function breakpoint, it isn't necessarily obvious why the debugger stopped.  There is no breakpoint glyph for a function breakpoint.  So if we return "function breakpoint", then VSCode will display "PAUSED ON FUNCTION BREAKPOINT" in the call stack viewlet.  Hopefully that will help the user know why the debugger stopped.

Author: rkeithhill

src/PowerShellEditorServices.Protocol/Server/DebugAdapter.cs

@@ -474,6 +474,21 @@ async void DebugService_DebuggerStopped(object sender, DebuggerStopEventArgs e)
             // Flush pending output before sending the event
             await this.outputDebouncer.Flush();
 
+            // Provide the reason for why the debugger has stopped script execution.
+            // See https://github.com/Microsoft/vscode/issues/3648
+            // The reason is displayed in the breakpoints viewlet.  Some recommended reasons are: 
+            // "step", "breakpoint", "function breakpoint", "exception" and "pause".
+            // We don't support exception breakpoints and for "pause", we can't distinguish 
+            // between stepping and the user pressing the pause/break button in the debug toolbar.
+            string debuggerStoppedReason = "step";
+            if (e.Breakpoints.Count > 0)
+            {
+                debuggerStoppedReason =
+                    e.Breakpoints[0] is CommandBreakpoint
+                        ? "function breakpoint"
+                        : "breakpoint";
+            }
+
             await this.SendEvent(
                 StoppedEvent.Type,
                 new StoppedEventBody
@@ -485,7 +500,7 @@ await this.SendEvent(
                     Line = e.InvocationInfo.ScriptLineNumber,
                     Column = e.InvocationInfo.OffsetInLine,
                     ThreadId = 1, // TODO: Change this based on context
-                    Reason = "breakpoint" // TODO: Change this based on context
+                    Reason = debuggerStoppedReason
                 });
         }