Add design right mark to latin plus

[davelab6]

from @tphinney

Seems like we have to keep an eye on EU design regulations. They are in the process of approving a new symbol for design protection, which could both be applied to fonts, and give us another character to support in fonts.

Capital D in a circle is already encoded at U+24B9, but not present in most fonts.

https://www.linkedin.com/pulse/here-comes-new-symbol-design-font-protection-production-type-44yie/