[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

simulation/halsim_ws_server/src/main/native/cpp/HALSimWSServer.cpp

@@ -9,6 +9,7 @@
 
 #include <WSProviderContainer.h>
 #include <WSProvider_Analog.h>
+#include <WSProvider_BuiltInAccelerometer.h>
 #include <WSProvider_DIO.h>
 #include <WSProvider_DriverStation.h>
 #include <WSProvider_Encoder.h>
@@ -37,6 +38,7 @@ bool HALSimWSServer::Initialize() {
 
     HALSimWSProviderAnalogIn::Initialize(registerFunc);
     HALSimWSProviderAnalogOut::Initialize(registerFunc);
+    HALSimWSProviderBuiltInAccelerometer::Initialize(registerFunc);
     HALSimWSProviderDIO::Initialize(registerFunc);
     HALSimWSProviderDigitalPWM::Initialize(registerFunc);
     HALSimWSProviderDriverStation::Initialize(registerFunc);