feat(x): Initialize project (#8999)

**Description:**

SWC X will be a cross-module optimizer that utilizes an enormous amount of information. After merging this, I'll experiment with several approaches.

Cargo.toml

@@ -21,6 +21,7 @@ members = [
   "crates/swc_plugin_proxy",
   "crates/swc_timer",
   "crates/swc_xml",
+  "crates/swc_x_optimizer",
 ]
 resolver = "2"
 

crates/swc_x_optimizer/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+authors     = ["강동윤 <kdy1997.dev@gmail.com>"]
+description = "Cross-module optimizer built on SWC"
+edition     = "2021"
+license     = "Apache-2.0"
+name        = "swc_x_optimizer"
+repository  = "https://github.com/swc-project/swc.git"
+version     = "0.1.0"
+
+
+[dependencies]

crates/swc_x_optimizer/src/lib.rs

@@ -0,0 +1,14 @@
+pub fn add(left: usize, right: usize) -> usize {
+    left + right
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let result = add(2, 2);
+        assert_eq!(result, 4);
+    }
+}