#[RichText]
Attribute on parameters and properties.
An inline field with HTML. Allowed on strings; the attribute gets
role: content. The framework does not restrict the markup: templates print
the value exactly as stored (|raw). WordPress filters it with wp_kses when
a user without unfiltered_html saves the post.
With postContent: true the value is not stored in the block comment but as
the block's inner HTML in the post content (inline HTML without wrapping
element, source: html); the framework passes it to the attribute class like
any other value. Allowed once per block, on a parameter of the block
attribute class itself, in blocks without inner blocks and with the default
''.