Construct Runtime v2 (#1378)

Moved from https://github.com/paritytech/substrate/pull/14788

----

Fixes https://github.com/paritytech/polkadot-sdk/issues/232

This PR introduces outer-macro approach for `construct_runtime` as
discussed in the linked issue. It looks like the following:
```rust
#[frame_support::runtime]
mod runtime {
	#[runtime::runtime]
        #[runtime::derive(
		RuntimeCall,
		RuntimeEvent,
		RuntimeError,
		RuntimeOrigin,
		RuntimeFreezeReason,
		RuntimeHoldReason,
		RuntimeSlashReason,
		RuntimeLockId,
                RuntimeTask,
	)]
	pub struct Runtime;

	#[runtime::pallet_index(0)]
	pub type System = frame_system;

	#[runtime::pallet_index(1)]
	pub type Timestamp = pallet_timestamp;

	#[runtime::pallet_index(2)]
	pub type Aura = pallet_aura;

	#[runtime::pallet_index(3)]
	pub type Grandpa = pallet_grandpa;

	#[runtime::pallet_index(4)]
	pub type Balances = pallet_balances;

	#[runtime::pallet_index(5)]
	pub type TransactionPayment = pallet_transaction_payment;

	#[runtime::pallet_index(6)]
	pub type Sudo = pallet_sudo;

	// Include the custom logic from the pallet-template in the runtime.
	#[runtime::pallet_index(7)]
	pub type TemplateModule = pallet_template;
}
```

## Features
- `#[runtime::runtime]` attached to a struct defines the main runtime
- `#[runtime::derive]` attached to this struct defines the types
generated by runtime
- `#[runtime::pallet_index]` must be attached to a pallet to define its
index
- `#[runtime::disable_call]` can be optionally attached to a pallet to
disable its calls
- `#[runtime::disable_unsigned]` can be optionally attached to a pallet
to disable unsigned calls
- A pallet instance can be defined as `TemplateModule:
pallet_template<Instance>`
- An optional attribute can be defined as
`#[frame_support::runtime(legacy_ordering)]` to ensure that the order of
hooks is same as the order of pallets (and not based on the
pallet_index). This is to support legacy runtimes and should be avoided
for new ones.

## Todo
- [x] Update the latest syntax in kitchensink and tests
- [x] Update UI tests
- [x] Docs

## Extension
- Abstract away the Executive similar to
https://github.com/paritytech/substrate/pull/14742
- Optionally avoid the need to specify all runtime types (TBD)

---------

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
Co-authored-by: Nikhil Gupta <>

substrate/frame/support/test/tests/runtime_ui/pass/basic.rs

@@ -0,0 +1,37 @@
+// 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::derive_impl;
+
+pub type Block = frame_system::mocking::MockBlock<Runtime>;
+
+#[derive_impl(frame_system::config_preludes::TestDefaultConfig as frame_system::DefaultConfig)]
+impl frame_system::Config for Runtime {
+	type Block = Block;
+}
+
+#[frame_support::runtime]
+mod runtime {
+    #[runtime::runtime]
+    #[runtime::derive(RuntimeCall, RuntimeEvent, RuntimeOrigin, RuntimeError, RuntimeTask)]
+    pub struct Runtime;
+
+    #[runtime::pallet_index(0)]
+    pub type System = frame_system;
+}
+
+fn main() {}