Allow `:text` key to in skia/paragraph accept styled text

[phronmophobic]

Currently, :text is expected to be a string, but if it could be arbitrarily styled text, then it would allow for nested styles.

For example:

{:text ["foo"
        {:text "bar"
         :style #:text-style {:font-style #:font-style {:weight :bold}}}
        "baz"]
 :style #:text-style {:font-families ["SF Pro"]}}