Fix issue where navigating to post after post creation throws error

[hjiangsu]

Pull Request Description

This is a small PR which fixes an issue where navigating to the post page after creation would throw an error. The issue comes from the fact that the new post page only accepts postViewMedia as a parameter (for now) rather than both postViewMedia or postId. Since the snackbar attempts to pass in a postId, the new post page is unable to use that information to load the post.

Luckily, the onPostSuccess returns back the full postViewMedia, so we can just use that!

Issue Being Fixed

Issue Number: #1413

Screenshots / Recordings

Checklist

• Did you update CHANGELOG.md?
• Did you use localized strings where applicable?
• Did you add semanticLabels where applicable for accessibility?

[micahmo]

Nice, glad this was an easy fix!