refactor: Add InteractionPart enum

[tienvx]

This code will be used later

Use case:

$driver->registerBody($interaction, InteractionPart::REQUEST);
$driver->registerBody($interaction, InteractionPart::RESPONSE);

public function registerBody(Interaction $interaction, InteractionPart $part): void
{
    $body = $part->isRequest() ? $interaction->getRequest()->getBody() : $interaction->getResponse()->getBody();
    ...
}

[Lewiscowles1986]

This feels like it's compensating for a lack of a getBody method on interaction, which should not care if the object is a request or a response.

[tienvx]

Added method getBody and getHeaders to Interaction

[tienvx]

Ping @Lewiscowles1986 . I think you miss this one

[tienvx]

Thank you. If you have additional ideas please continue comment to this discussion