[DiagnosticsClient] Add SupportsEventPipeUserEventsCommand APIs

Author: mdh1418

docs/core/diagnostics/microsoft-diagnostics-netcore-client.md

@@ -47,6 +47,11 @@ public sealed class DiagnosticsClient
         EventPipeSessionConfiguration configuration,
         CancellationToken token);
 
+    public bool SupportsEventPipeUserEventsCommand();
+
+    public Task<bool> SupportsEventPipeUserEventsCommandAsync(
+        CancellationToken token = default);
+
     public void WriteDump(
         DumpType dumpType,
         string dumpPath,
@@ -169,6 +174,19 @@ Starts an EventPipe tracing session using an [`EventPipeSessionConfiguration`](#
 * `config` / `configuration` : An `EventPipeSessionConfiguration` that defines the session.
 * `token` (for the async overload): The token to monitor for cancellation requests.
 
+### SupportsEventPipeUserEventsCommand methods
+
+```csharp
+public bool SupportsEventPipeUserEventsCommand();
+
+public Task<bool> SupportsEventPipeUserEventsCommandAsync(
+    CancellationToken token = default);
+```
+
+Checks whether the target runtime understands the `CollectTracing5` `user_events` IPC command.
+
+* `token` (for the async overload): The token to monitor for cancellation requests.
+
 > [!NOTE]
 > Rundown events contain payloads that may be needed for post analysis, such as resolving method names of thread samples. Unless you know you do not want this, we recommend setting `requestRundown` to true. In large applications, this may take a while.