refactor project structure (start of redoing atomic branch without atomics)

macro/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "iris-macro"
+version.workspace = true
+edition.workspace = true
+
+[dependencies]
+quote = "1.0.42"
+syn = { version = "2.0.111", features = ["full"] }
+
+[lib]
+proc-macro = true