[WIP] PSM Step 1

This is totally WIP.
I just tested this with putting `<div class="right-outlet">` inside `post-settings-sidebar.hbs`

It works well enough, but because `<div class="right-outlet">` is only appended to the page after the PSM button is clicked, the animation doesn't happen - it just snaps to the correct position, which isn't a big deal, but kinda annoying. If `<div class="right-outlet">` is there _before_ the PSM starts to open (i.e. on view render), it'll be fine.