Add support for all elements in the `RichText` parser

[Sub6Resources]

The following still need support in the RichText version of the parser:

• address
• aside
• bdi
• bdo (Too complicated to implement without official support in the Flutter framework for this)
• big
• cite
• data
• del
• ins
• kbd
• mark
• nav
• noscript
• q
• rp
• rt
• ruby
• s
• samp
• span
• strike
• sub
• sup
• template
• time
• tt
• var

[The-Redhat]

Although the HtmlRichTextParser doesn't support span, it would be great if it simply shows the content. Now it's looking really weird, because text is missing.

[Sub6Resources]

Support for span has been added in version 0.9.5.

[Sub6Resources]

Support for address added in 0.9.8.