Use dataclass for email data

[mtomilov]

Refs #9332

Now that we've added tag to email data it makes sense to incapsulate it all in a separate class and pass it around instead of a tuple.

Testing

• Log in as devdata_admin:pass
• Try resetting the password using admin@example.com email
• Try signing up for the account
• Try creating an annotation reply
  See Don't send multiple emails on reply with mentions #9356 for instructions
• Try creating an annotation with mentions
  See Don't send multiple emails on reply with mentions #9356 for instructions
• Try flagging your own annotation as devdata_biopub_creator in biopub open group
• Check /mail folder for new emails

To test support of both send signatures you can run something like this from the cli.

    email = EmailData(
        recipients=["example.com"],
        subject="My email subject",
        body="Some text body",
        tag=EmailTag.TEST,
        html="<p>An HTML body</p>",
    )
    mailer.send.delay(email)
    mailer.send.delay(recipients=email.recipients, subject=email.subject, body=email.body, tag=email.tag, html=email.html)

[mtomilov]

Moving the types to the signature of the function

[mtomilov]

Incapsulating converting the email data into pyramid mailer message

[mtomilov]

Enabling pickle to support dataclass serialization just for this task

[mtomilov]

Letting the workers accept pickled dataclass serialization
Not sure what are policy here is but having to stick to json-serializable is kinda limiting.
Alternatively we could write our own serializer / deserializer pair and register it with kombu.serialization to be more explicit with what we send and receive.

[mtomilov]

Number of arguments doesn't change but we support both old and new signatures by inspecting the type of the first argument below to support in-flight celery tasks with the old arguments.