[sim] Various WebSockets fixes and enhancements (#2952)

This is a breaking change to the WebSockets layer to align it with
recent specification documentation work.

To support this, HAL SimValue changed readonly to a direction enum.
This allows specifying bidirectional in addition to input and output.

The SimValue change is specifically designed to avoid API and ABI breakage.
This is completely transparent in C++; in Java a new callback class was added,
and the old readonly functions have been marked deprecated.

A new SimValue creation function for enums allows specifying double values
for each enum value, not just strings.  This allows mapping enum values to
doubles in the WebSockets layer.

A ":" in the SimDevice name now maps it to different WebSocket types (e.g.
"Accel:Name" becomes type "Accel", device "Name").  The type is hidden
in the GUI.

Other WebSockets changes:
* Implemented match_time and game_data
* Added joystick rumble data
* Added builtin accelerometer support
* SimValue enums are mapped to string and double value on WS interface
* Added WebSockets protocol specification
* Added READMEs

hal/src/main/native/athena/mockdata/SimDeviceData.cpp

@@ -74,6 +74,12 @@ const char** HALSIM_GetSimValueEnumOptions(HAL_SimValueHandle handle,
   return nullptr;
 }
 
+const double* HALSIM_GetSimValueEnumDoubleValues(HAL_SimValueHandle handle,
+                                                 int32_t* numOptions) {
+  *numOptions = 0;
+  return nullptr;
+}
+
 void HALSIM_ResetSimDeviceData(void) {}
 
 }  // extern "C"