[RadialGauge] Set ToolTip

[niels9001]

Addressing: #114

[michael-hawker]

Weird:

  Passed DispatcherQueueHelper_FuncOfTaskOfT_Ok_From_NonUIThread_DispatcherQueueExtensionTests_Test [6 ms]
The active test run was aborted. Reason: Unable to communicate with test host process.
Terminating app with process ID '1608'.
Results File: D:\a\Windows\Windows\TestResults\WinAppSdk.trx

Test Run Aborted with error System.AggregateException: One or more errors occurred. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
Total tests: Unknown
   at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)

I've rerun the pipeline...