Add the aegraph (acyclic e-graph) implementation crate. (#4909)

* Add the aegraph (acyclic egraph) implementation crate.

* fix crate-dep version for cranelift-entity (rebase error)

* Review feedback.

* Fix link in Markdown doc comment.

* Doc link fix again.

* add cranelift-egraph to publish list.

Cargo.lock

@@ -557,6 +557,18 @@ dependencies = [
 name = "cranelift-codegen-shared"
 version = "0.89.0"
 
+[[package]]
+name = "cranelift-egraph"
+version = "0.89.0"
+dependencies = [
+ "cranelift-entity",
+ "fxhash",
+ "hashbrown",
+ "indexmap",
+ "log",
+ "smallvec",
+]
+
 [[package]]
 name = "cranelift-entity"
 version = "0.89.0"
@@ -1328,9 +1340,9 @@ checksum = "eabb4a44450da02c90444cf74558da904edde8fb4e9035a9a6a4e15445af0bd7"
 
 [[package]]
 name = "hashbrown"
-version = "0.12.1"
+version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "db0d4cf898abf0081f964436dc980e96670a0f36863e4b83aaacdb65c9d7ccc3"
+checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
 dependencies = [
  "ahash",
 ]