Make SerializerOptions public property of IManagementClient

[inikulshin]

It can be useful for logging.
And for serializing Infos for some of rabbitmqctl commands that require JSON parameters, like set_parameter or set_policy.

@Pliner @zidad wdyt?

[inikulshin]

Maybe, more generic is to add

public string Serialize<TValue>(TValue value)

JsonSerializerOptions requires System.Text.Json, which is implementation details.