Move PalletVersion away from the crate version (#9165)

* Move `PalletVersion` away from the crate version

Before this pr, `PalletVersion` was referring to the crate version that
hosted the pallet. This pr introduces a custom `package.metadata.frame`
section in the `Cargo.toml` that can contain a `pallet-version` key
value pair. While the value is expected to be a valid u16. If this
key/value pair isn't given, the version is set to 1.

It also changes the `PalletVersion` declaration. We now only have one
`u16` that represents the version. Not a major/minor/patch version. As
the old `PalletVersion` was starting with the `u16` major, decoding the
old values will work.

* Overhaul the entire implementation

- Drop PalletVersion
- Introduce StorageVersion
- StorageVersion needs to be set in the crate and set for the macros
- Added migration

* Fix migrations

* Review feedback

* Remove unneeded dep

* remove pub consts

* Brings back logging and implements `GetStorageVersion`

* Return weight from migration

* Fmt and remove unused import

* Update frame/support/src/dispatch.rs

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

* Update frame/support/src/traits/metadata.rs

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

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

substrate/frame/contracts/src/lib.rs

@@ -111,7 +111,7 @@ use crate::{
 };
 use frame_support::{
 	dispatch::Dispatchable,
-	traits::{Currency, Filter, Get, OnUnbalanced, Randomness, Time},
+	traits::{Currency, Filter, Get, OnUnbalanced, Randomness, StorageVersion, Time},
 	weights::{GetDispatchInfo, PostDispatchInfo, Weight, WithPostDispatchInfo},
 };
 use frame_system::Pallet as System;
@@ -134,6 +134,9 @@ type NegativeImbalanceOf<T> = <<T as Config>::Currency as Currency<
 	<T as frame_system::Config>::AccountId,
 >>::NegativeImbalance;
 
+/// The current storage version.
+const STORAGE_VERSION: StorageVersion = StorageVersion::new(4);
+
 #[frame_support::pallet]
 pub mod pallet {
 	use super::*;
@@ -273,6 +276,7 @@ pub mod pallet {
 	}
 
 	#[pallet::pallet]
+	#[pallet::storage_version(STORAGE_VERSION)]
 	pub struct Pallet<T>(PhantomData<T>);
 
 	#[pallet::hooks]