[WIP] Remove ref to html-minifier/js-beautify/migrate

[iRyusa]

Not tested yet.

• Need to write doc about how to keep the feature available for users.
• Check how to handle this case in mjml-browser

[phlogisticfugu]

@iRyusa - is this PR still the direction you want to go?

we want to use mjml, but currently cannot due to vulnerabilities in html-minifier and js-beautify

if you are open to PRs, could help with removing them

also, see in https://github.com/mjmlio/mjml/commits/v5.0.0-alpha.1/ that you more recently were thinking of replacing them.

[iRyusa]

Hi @phlogisticfugu ,
Minifier seem to be mandatory for MJML as it can prevent some bugs in some email clients, so yeah removing doesn't seem the best solution in our case.
For js-beautify, it's a different story as it make the "raw" output from MJML somewhat readable. I don't think this is a mandatory feature, but I think it's better to have a properly formatted output.