SSBC: Share more code between Workspaces Preview and Execution Workspaces

Created by: courier-new

We've built and are expanding two separate components for "a list of workspaces" -- the first is the Workspaces Preview for the editor screen, and the second is the Execution Workspaces for the execution screen. Because these are styled and maintained separately, they are not visually consistent with each other and duplicate filter/search logic between them. We should devise a way to share code between these without sacrificing code legibility (e.g. without introducing tons of ternaries or complicated props).