migrations: VersionedRuntimeUpgrade (#14311)

* VersionedRuntimeUpgrade

* only require one version and add a pre-upgrade check

* add docs

* improve warning log

* improve comments

* fix log

* use associated constants

* allow passing from and to versions

* test versioned_runtime_upgrade

* fix typo

* improve docs

* docs

* docs

* remove event from dummy pallet

* remove pre_upgrade current storage version check

* derive_impl

* skip pre/post checks if the actual migration will not run

* improve variable naming

* docs

* fix post_upgrade 'should run' logic

* fix comments

* pre and post hook tests

* feature gate try-runtime stuff

* remove deprecated macro

* Update frame/support/src/migrations.rs

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* decode_all

* make experimental

* use rust generics

* add info log when running

* simplify tests

* improve log

* improve log

* cleaner pre_upgrade encoding

* Update frame/support/src/migrations.rs

Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

* Update frame/support/src/migrations.rs

Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

* Update frame/support/src/migrations.rs

Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

* Update frame/support/src/migrations.rs

Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

* Update frame/support/src/migrations.rs

Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

* VersionedPostUpgradeData enum

* move versioned runtime upgrade tests to test/tests

* fix rust doc

* clarify comment

---------

Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Gonçalo Pestana <g6pestana@gmail.com>

substrate/frame/support/test/Cargo.toml

@@ -54,6 +54,7 @@ std = [
 	"sp-version/std",
 	"test-pallet/std",
 ]
+experimental = ["frame-support/experimental"]
 try-runtime = [
 	"frame-support/try-runtime",
 	"frame-system/try-runtime",