Fuzzer for Pallet Bags List (#9851)

* Fuzzer for Pallet Bags List

* Some small updates

* Fuzzer for Pallet Bags List

This PR adds a fuzzer for the `SortedListProvider` API exposed by pallet-bags-list.

* Feature gate code NOT used by fuzz feature

* Create Enum for list actions

* fix some small mistakes

* try and make CI happy

* fmt

* Do not insert before updating

* clean up some misc. comments

* marginally improve Node::sanity_check

* Change ID_RANGE to 25_000

* comma

* try improve correct feature gating so no unused code

Co-authored-by: thiolliere <gui.thiolliere@gmail.com>

substrate/frame/bags-list/fuzzer/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "pallet-bags-list-fuzzer"
+version = "4.0.0-dev"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+license = "Apache-2.0"
+homepage = "https://substrate.dev"
+repository = "https://github.com/paritytech/substrate/"
+description = "Fuzzer for FRAME pallet bags list"
+readme = "README.md"
+publish = false
+
+[dependencies]
+honggfuzz = "0.5"
+rand = { version = "0.8", features = ["std", "small_rng"] }
+
+pallet-bags-list = { version = "4.0.0-dev", features = ["fuzz"], path = ".." }
+frame-election-provider-support = { version = "4.0.0-dev", path = "../../election-provider-support", features = ["runtime-benchmarks"] }
+
+[[bin]]
+name = "bags-list"
+path = "src/main.rs"