Consider multiple input_accepted topics

[MattWindsor91]

Right now, the tester generates only one callback (and ROS subscription) for input acceptance. Discussion with @pefribeiro suggests we may need to generalise this when we start accepting multiple inputs, so that we can understand which input has been received.

Some relevant bits of code that might need to change are as follows. Generally, wherever we have .Transitions.HasIn, we'd need to range over the input channels (.Transitions.In should work, since we hopefully don't need to consider the possibility of the system acknowledging inputs we don't control, unlike the situation with #14 and output transitions).

Here (callback prototypes):

rtcg/internal/gen/cpp/embed/templates/base/stm.cpp.tmpl

Lines 23 to 25 in a10b169

	{{- if .Transitions.HasIn }}
	void inputAcceptedCallback({{ template "in_callback_args" }}); // Called when the SUT accepts an input.
	{{- end }}

And here (callback definitions; maybe we can get rid of InMerged):

rtcg/internal/gen/cpp/embed/templates/base/stm.cpp.tmpl

Lines 114 to 122 in a10b169

	{{- if .Transitions.HasIn }}
	void StateMachine::inputAcceptedCallback({{ template "in_callback_args" }})
	{
	{{- block "in_callback" .Transitions.InMerged }}
	{{- template "in_callback.cpp.tmpl" . }}
	{{- end -}}
	}
	{{- end }}

And, in the animator, here (generalise to one menu item per input channel?):

rtcg/internal/gen/cpp/embed/templates/animate/main_body.cpp.tmpl

Lines 37 to 40 in a10b169

	{{- if .Transitions.HasIn }}
	else if (choice == "accept" && s == rtcg::Status::WAIT_IN)
	stm.inputAcceptedCallback();
	{{- end }}

And, in ROS, here (generalise to one subscriber per input channel?):

rtcg/internal/gen/cpp/embed/templates/ros/main.cpp.tmpl

Lines 60 to 62 in a10b169

	{{- if .Transitions.HasIn }}
	auto input_accepted_sub = nh.subscribe("input_accepted", 10, &StateMachine::inputAcceptedCallback, &stm);
	{{- end }}

The situation with the input delay callbacks may also need some reworking, but I'm not yet sure how.