Add maizzle send command

[wzrdjstr]

Maizzle's dev server is good for initial prototyping but rendering is notoriously inconsistent across mail clients.

It would be nice to have a maizzle send CLI command which sends an email to one or more email addresses, so it's easier to preview emails in actual mail clients and integrate Maizzle with automated test frameworks for e2e testing.

Being able to configure multiple test recipients (test@gmail.com, test@outlook.com) makes it easier to preview templates in multiple mail clients simultaneously.

For example:

Maizzle could have a send config which contains defaults for the maizzle send command, which are merged with parameters provided on the command line at run time.

This config could be used to setup a node-mailer instance which sends a single template (or all templates if none is specified) to the configured recipient addresses.

A button could be added to the maizzle serve web UI to manually send templates (using config defaults).

[wzrdjstr]

I can work on this but I'd prefer to wait until vuejs/v6 refactor, if that's still in the pipeline.

[cossssmin]

It'll be easier to provide integration guides, people use all sorts of services to send email and tbh I'm not looking forward to maintaining something like that. Guides we can do, people can just follow them to hook up Maizzle to their sending platform 👍