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/zed/src/assets.rs

@@ -1,20 +0,0 @@
-use anyhow::{anyhow, Result};
-use gpui::AssetSource;
-use rust_embed::RustEmbed;
-
-#[derive(RustEmbed)]
-#[folder = "assets"]
-#[exclude = "*.DS_Store"]
-pub struct Assets;
-
-impl AssetSource for Assets {
-    fn load(&self, path: &str) -> Result<std::borrow::Cow<[u8]>> {
-        Self::get(path)
-            .map(|f| f.data)
-            .ok_or_else(|| anyhow!("could not find asset at path \"{}\"", path))
-    }
-
-    fn list(&self, path: &str) -> Vec<std::borrow::Cow<'static, str>> {
-        Self::iter().filter(|p| p.starts_with(path)).collect()
-    }
-}