Classic Text block still has "Freeform" tag name

[hedgefield]

When you add a Classic Text block (the name of which we settled on in #1326), the code version still looks like

<!-- wp:core/freeform -->
<p class="wp-block-freeform"></p>
<!-- /wp:core/freeform -->

If we're gonna commit to the name we should also change the tag.

Version 0.3.0

[youknowriad]

This won't harm backwards compatibility since it's the default block used if no matching block is found.

[mtias]

The plan is to not show comment/name for this block.