Align resource model name to type name

[pshao25]

For such resource model

model DatadogMonitorResource
  extends Azure.ResourceManager.Foundations.TrackedResource {
  ...ResourceNameParameter<
    Resource = DatadogMonitorResource,
    KeyName = "monitorName",
    SegmentName = "monitors",
    NamePattern = ""
  >;

Expected:

model Monitor
  extends Azure.ResourceManager.Foundations.TrackedResource {
  ...ResourceNameParameter<
    Resource = Monitor,
    KeyName = "monitorName",
    NamePattern = ""
  >;

@@clientName(Monitor, DatadogMonitorResource);

And the filename should be monitor.ts.