Chore: Refactor text preview for MediaView

[hjiangsu]

Pull Request Description

This PR is one of a few refactors I'll be doing to the general MediaView widget. Right now, the MediaView widget is a bit complicated and can be improved by splitting it up into smaller widgets, each handling a different type of media (e.g., image, video, text, link).

Since MediaView is used pretty much everywhere (e.g., feed pages, account page, post page, etc.), refactoring this widget to be easier to maintain and potentially more performant would be good!

For this specific PR, I've extracted out the text portion of MediaView into its own widget (MediaViewText), and moved MediaView into the /shared/media directory. I've also cleaned up the MediaViewText widget a little bit!

Issue Being Fixed

Issue Number: N/A

Screenshots / Recordings

Checklist

• If a new package was added, did you ensure it uses an appropriate license and is actively maintained?
• Did you use localized strings (and added appropriate descriptions) where applicable?
• Did you add semanticLabels where applicable for accessibility?

[micahmo]

Very nice!