Extract Clojure support into an extension (#10088)

This PR extracts Clojure support into an extension and removes the
built-in Clojure support from Zed.

Release Notes:

- Removed built-in support for Clojure, in favor of making it available
as an extension. The Clojure extension will be suggested for download
when you open a `.clj` or other Clojure-related files.

---------

Co-authored-by: Max <max@zed.dev>

extensions/clojure/languages/clojure/highlights.scm

@@ -0,0 +1,41 @@
+;; Literals
+
+(num_lit) @number
+
+[
+  (char_lit)
+  (str_lit)
+] @string
+
+[
+ (bool_lit)
+ (nil_lit)
+] @constant.builtin
+
+(kwd_lit) @constant
+
+;; Comments
+
+(comment) @comment
+
+;; Treat quasiquotation as operators for the purpose of highlighting.
+
+[
+ "'"
+ "`"
+ "~"
+ "@"
+ "~@"
+] @operator
+
+
+(list_lit
+  .
+  (sym_lit) @function)
+
+(list_lit
+  .
+  (sym_lit) @keyword
+  (#match? @keyword
+    "^(do|if|let|var|fn|fn*|loop*|recur|throw|try|catch|finally|set!|new|quote|->|->>)$"
+    ))