Move assets to their own crate, load keymaps in vim tests

Also, move assets folder to the top-level.

Co-authored-by: Keith Simmons <keith@zed.dev>

crates/settings/Cargo.toml

@@ -11,6 +11,7 @@ doctest = false
 test-support = []
 
 [dependencies]
+assets = { path = "../assets" }
 collections = { path = "../collections" }
 gpui = { path = "../gpui" }
 theme = { path = "../theme" }