Follow up to https://github.com/zed-industries/zed/pull/42819 and https://github.com/zed-industries/zed/pull/44206. - Make this picker feel more consistent with other similar pickers (namely, the project picker) - Move actions to the footer and toggle them conditionally - Only show the "Create" and "Create New From: {default}" when we're selecting the "Create" list item _or_ when that item is the only visible. This means I'm changing here the state transition to only change to `NewBranch/NewRemote` if we only have those items available. - Reuse more UI code and use components when available (e.g., `ListHeader`) - Remove secondary actions from the list item Next step (in another PR), will be refine the same picker in the smaller, panel version. https://github.com/user-attachments/assets/fe72ac06-c1df-4829-a8a4-df8a9222672f Release Notes: - N/A