initial version of annotation formatting

compiler/fmt/src/lib.rs

@@ -10,6 +10,7 @@
 // and encouraging shortcuts here creates bad incentives. I would rather temporarily
 // re-enable this when working on performance optimizations than have it block PRs.
 #![allow(clippy::large_enum_variant)]
+pub mod annotation;
 pub mod def;
 pub mod expr;
 pub mod module;