[FRAME Core] Adds ability to split a pallet across multiple files (#13950)

* Initial setup

* Updates macro_magic version and refactors accordingly

* Removes unwrap from macro

* Splits into multiple sections

* Uses call_site to fix macro hygiene issue

* Initial setup

* Removes unnecessary changes

* Moves template palet back

* Updates cargo.lock

* Moves BagsList inside mod

* Comments access to internal functions for now

* Updates tests

* Uncomments code

* Fixes test

* Moves bags-list to separate crate

* Initial setup

* Removes bags-list changes

* Fix structure

* Minor update

* Addresses review comment

* Adds a couple of UI tests. More to be added

* Adds err files

* Adds test for no pallet

* Adds doc

* Updates versions

* Adds benchmarking

* Updates doc link

* ".git/.scripts/commands/fmt/fmt.sh"

* Minor update

* Adds missing changes

* ".git/.scripts/commands/fmt/fmt.sh"

* Update frame/support/procedural/src/lib.rs

Co-authored-by: Sam Johnson <sam@durosoft.com>

* Addresses review comments

* Addresses review comments

* ".git/.scripts/commands/fmt/fmt.sh"

* Update frame/support/procedural/src/lib.rs

Co-authored-by: Sam Johnson <sam@durosoft.com>

* Update frame/support/procedural/src/lib.rs

Co-authored-by: Sam Johnson <sam@durosoft.com>

* Update frame/support/procedural/src/lib.rs

Co-authored-by: Sam Johnson <sam@durosoft.com>

* Adds UI test for disambiguation

* ".git/.scripts/commands/fmt/fmt.sh"

* Makes clippy happy

* ".git/.scripts/commands/fmt/fmt.sh"

* Fixes frame support test

* Fixes frame support test

* Split items other than storage

* Updates versions

* Fixes some review comments

* Addresses review comments

* ".git/.scripts/commands/fmt/fmt.sh"

* Updates docs

* Adds experimental disclaimer

* ".git/.scripts/commands/fmt/fmt.sh"

* Update frame/support/test/tests/split_ui/no_section_found.rs

Co-authored-by: Sam Johnson <sam@durosoft.com>

* Addresses review comments

* Fixes test

---------

Co-authored-by: command-bot <>
Co-authored-by: command-bot <ci@gitlab.parity.io>
Co-authored-by: Sam Johnson <sam@durosoft.com>

substrate/frame/examples/split/src/events.rs

@@ -0,0 +1,31 @@
+// This file is part of Substrate.
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use frame_support::pallet_macros::*;
+
+/// A [`pallet_section`] that defines the events for a pallet.
+/// This can later be imported into the pallet using [`import_section`].
+#[pallet_section]
+mod events {
+	#[pallet::event]
+	#[pallet::generate_deposit(pub(super) fn deposit_event)]
+	pub enum Event<T: Config> {
+		/// Event documentation should end with an array that provides descriptive names for event
+		/// parameters. [something, who]
+		SomethingStored { something: u32, who: T::AccountId },
+	}
+}