Theme preview link can be inaccurate

[anthmatic]

Description and Context

While looking into #596 I did found a flaw in the way this link is generated. If the theme is uploaded to a different folder, the preview link will not be accurate

Steps to reproduce

hs upload "cool theme" theme2000 would yield a link to /theme-previewer/1234567/edit/cool%20theme when it should point to /theme-previewer/1234567/edit/theme2000

Expected behavior

Theme preview link should be based on the destination path in the developer filesystem

Screenshots

Who to Notify