Make InvalidEventHandler signature consistent with normal EventHandlers

Summary:
This brings two benefits:

1. The unspecialized EventHandler that calls `SM::InvalidEventHandler` can now simply tail call `InvalidEventHandler`. Prior to this diff, the call to `InvalidEventHandler` depended on the `event` non-type template parameter, which meant that _every_ invalid transition would result in a separate instantiation with distinct code in order to set up the event argument.
2. In a future diff, we can leave the default EventHandler unimplemented and SFIANE the instantiation in `getEventHandler`.

Before:
```
   45594:       f81f0ffe        str     x30, [sp, #-16]!
   45598:       aa0103e2        mov     x2, x1
   4559c:       52800181        mov     w1, #0xc                        // #12
   455a0:       97ffa9dc        bl      2fd10 <_ZN4fizz6client6detail18handleInvalidEventERKNS0_5StateENS_5EventERNS_5ParamE>
```

After:
```
0000000000045374 <_ZN4fizz2sm12EventHandlerINS_6client11ClientTypesELNS2_9StateEnumE3ELNS_5EventE12EE6handleERKNS2_5StateES5_RNS_5ParamE>:
   45374:       f81f0ffe        str     x30, [sp, #-16]!
   45378:       97ffaa68        bl      2fd18 <_ZN4fizz6client6detail18handleInvalidEventERKNS0_5StateENS_5EventERNS_5ParamE>
```

Reviewed By: zalecodez, knekritz

Differential Revision: D58147022

fbshipit-source-id: aa7075ad03528234ef0cd1090d5e9e3629076135

fizz/client/ClientProtocol.cpp

@@ -335,7 +335,8 @@ Actions handleAppClose(const State& state) {
   }
 }
 
-Actions handleInvalidEvent(const State& state, Event event, Param& param) {
+Actions handleInvalidEvent(const State& state, Param& param) {
+  auto event = EventVisitor()(param);
   if (event == Event::Alert) {
     auto& alert = *param.asAlert();
     throw FizzException(

fizz/client/ClientProtocol.h

@@ -67,7 +67,7 @@ Actions handleError(
 Actions handleAppCloseImmediate(const State& state);
 Actions handleAppClose(const State& state);
 
-Actions handleInvalidEvent(const State& state, Event event, Param& param);
+Actions handleInvalidEvent(const State& state, Param& param);
 } // namespace detail
 
 struct ClientTypes {

fizz/protocol/StateMachine-inl.h

@@ -49,7 +49,7 @@ class EventHandler : public EventHandlerBase<SM, state, event> {
   static typename SM::Actions handle(
       const typename SM::State& curState,
       typename SM::Param& param) {
-    return SM::InvalidEventHandler(curState, event, param);
+    return SM::InvalidEventHandler(curState, param);
   }
 };
 

fizz/server/ServerProtocol.cpp

@@ -337,7 +337,8 @@ Actions handleAppClose(const State& state) {
   }
 }
 
-Actions handleInvalidEvent(const State& state, Event event, Param& param) {
+AsyncActions handleInvalidEvent(const State& state, Param& param) {
+  auto event = EventVisitor()(param);
   if (event == Event::Alert) {
     auto& alert = *param.asAlert();
     throw FizzException(

fizz/server/ServerProtocol.h

@@ -67,7 +67,7 @@ Actions handleError(
 Actions handleAppCloseImmediate(const State& state);
 Actions handleAppClose(const State& state);
 
-Actions handleInvalidEvent(const State& state, Event event, Param& param);
+AsyncActions handleInvalidEvent(const State& state, Param& param);
 } // namespace detail
 
 struct ServerTypes {