Context used for Atom interface should be custom and supply the necessary integrations for the other parameters of the Process method

[benjivesterby]

This change would reduce the number of expected parameters for the Process method to only context.Context which should be supplied by the Atomizer engine. Since context.Context is an interface the Atomizer engine should implement the interface internally and supply an Atomizer Context which when used in conjunction with a type assertion can give access to the Atomizer communication API as well as other necessary engine APIs.