Use a json encoder that supports private fields in golang

[symbiont-stevan-andjelkovic]

In order to be able to make assertions about how the state of all components changes over time and to make debugging easier, we dump and save the state of components in json format when they receive an event.

In golang we currently use encoding/json for this, but given that it simply drops private fields this isn't ideal (which leads to workarounds such as introducing an extra datatype which exposes the private fields).

Perhaps an other library which also encodes private fields can be used, e.g. https://github.com/json-iterator/go.

[symbiont-stevan-andjelkovic]

This can be achieved with json-iterator by calling SupportPrivateFields() in executor before dumping the heap. However this call mutates global state in the json-iterator library, so in case the SUT also used json-iterator it might cause the SUT to encode private fields in the JSON output.

The above problem can be avoided by creating an explicit json-iterator config instead of relying on the implicit global one:

	cfg := jsoniter.Config{}.Froze()
	cfg.RegisterExtension(&jsoniter.privateFieldsExtension{})
	str, err := cfg.Marshal(&obj)

For some reason privateFieldsExtension struct seems to be private, so maybe a one byte upsteam change is needed, meanwhile the code for the extension could be copy pasted into our code base.

Also note that the fields containing zap.Loggers should be marked with json:"-", in particular zap.NewProduction() seems to cause an infinite loop when encoded, while zap.NewDevelopment causes an encoding error.