Fix memory leak in require (#6790)

* Fix memory leak in require() and add test

* Mark fixtures as generated code

* Add optimization for large files

* Fix small memory leak

---------

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>

src/string.zig

@@ -846,6 +846,10 @@ pub const String = extern struct {
         }
     }
 
+    pub fn eqlUTF8(this: String, other: []const u8) bool {
+        return this.toZigString().eql(ZigString.initUTF8(other));
+    }
+
     pub fn eql(this: String, other: String) bool {
         return this.toZigString().eql(other.toZigString());
     }