Allow the usage of personalisation data on endpoint "/marketing/test/send_email"

[thiagobarbosa]

Issue Summary

Currently the endpoint POST /v3/marketing/test/send_email does not accept any personalisation data in the request.
Since the whole point of the dynamic templates is to have personalised data coming from APIs, this endpoint cannot be used for actual realistic tests.
Additionally, since this is the only endpoint that allows you to explicitly use some template version (instead of defaulting to the active one), it makes super difficult to change production emails without having to duplicate templates all over the place.

This whole thing of "how to have stage/production version of the templates" is its own topic, but it would be great if the /marketing/test/send_email endpoint accepted a personalisation object so we can test the template with all the dynamic data it uses.

[github-actions]

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