Generate newsletter HTML from the data

[mrchrisadams]

When people submit a job add, we currently support the markdown that slack supports.

This allows folks to add links, and some basic formatting.

It would be nice to have this same kind of support in newsletter, but we have a few problems:

1. Slack's flavour of markdown is a dialect called mrkdwn, which is not the same.
2. Unsurprisingly, there is no MrkdwnService exposed in Google Appscript. So we'd need to find something like an implementation of this, that we can upload into scope, and then make sure we can use it from Code.js.

A way we might do this

From what I can see, Appscript needs the final objects to exist as Global objects in order to make them available, which is pretty much the opposite of how most bundlers want to work.

It looks like a way we would have to do this would be to use something like Rollup as suggested in the clasp docs, and then use that to require some library that can speak mrkdwn, to render it as html that could go into an HTML email.

However, this is stretching my knowledge of the Javascript ecosystem. I'm parking this here to see if any kind souls might know a better way to do this - I have seen some code examples using webpack to build bundles for use, but I've been trying to avoid relying on it, as everytime I touch webpack I end being overwhelmed by the complexity :(