BUG: Parser breaks `mj-style` as of 16.30

Version:

All Grapesjs version from 16.30 to now have this issues.

Are you able to reproduce the bug from the demo?

• Yes
• No

What is the expected behavior?

The following is valid MJML code. It should work fine on grapesjs-mjml.

<mjml>
  <mj-head>
    <mj-style>
      @font-face {
        font-family: "foo";src: url('./fonts/foo.otf') format('truetype');
      }
    </mj-style>
  </mj-head>
<mj-body>

Describe the bug detailed

Right now, if you use grapesjs-mjml with the code above it will break in 2 ways:

1. It will render the style like this:

@font-face {font-family: "foo";src: url('./fonts/foo') format('truetype');}

2. When you export the code, it exports the MJML code as the following:

<mjml>
  <mj-head>
    <mj-style>
      @font-face {
      font-family: &quot;foo&quot;;src: url(&#039;./fonts/foo.otf&#039;) format(&#039;truetype&#039;);
      }
    </mj-style>
  </mj-head>
  <mj-body>
  </mj-body>
</mjml>

In both cases, you can see that the style has been html-encoded.

What is the current behavior?

mj-style is not a textNode and it's content must not be htmlEncoded.

Describe the bug detailed

The reason I'm filing this against this repository and not grapesjs-mjml is this: This regression is a result of commit 8e7f94abb0c4500cebde5a4984eca4215772cb0b.

As of this commit, grapesjs wrongly assumes all textNode's are, well, textNode's. That's not always the case (like mj-style).

Are you able to attach screenshots, screencasts or a live demo?