Extract Scheme and Racket language support into extensions (#10442)

Release Notes:

- Extracted Scheme and Racket language support into extensions.

---------

Co-authored-by: Marshall <marshall@zed.dev>

crates/extensions_ui/src/extension_suggest.rs

@@ -52,7 +52,9 @@ const SUGGESTIONS_BY_EXTENSION_ID: &[(&str, &[&str])] = &[
     ("prisma", &["prisma"]),
     ("purescript", &["purs"]),
     ("r", &["r", "R"]),
+    ("racket", &["rkt"]),
     ("sql", &["sql"]),
+    ("scheme", &["scm"]),
     ("svelte", &["svelte"]),
     ("swift", &["swift"]),
     ("templ", &["templ"]),