Move weight constants to own mod (#10980)

* Move block+ext weights to own mod

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Unused import

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

substrate/frame/support/src/weights/block_weights.rs

@@ -0,0 +1,46 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 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.
+
+pub mod constants {
+	use frame_support::{
+		parameter_types,
+		weights::{constants, Weight},
+	};
+
+	parameter_types! {
+		/// Importing a block with 0 Extrinsics.
+		pub const BlockExecutionWeight: Weight = 5_000_000 * constants::WEIGHT_PER_NANOS;
+	}
+
+	#[cfg(test)]
+	mod test_weights {
+		use frame_support::weights::constants;
+
+		/// Checks that the weight exists and is sane.
+		// NOTE: If this test fails but you are sure that the generated values are fine,
+		// you can delete it.
+		#[test]
+		fn sane() {
+			let w = super::constants::BlockExecutionWeight::get();
+
+			// At least 100 µs.
+			assert!(w >= 100 * constants::WEIGHT_PER_MICROS, "Weight should be at least 100 µs.");
+			// At most 50 ms.
+			assert!(w <= 50 * constants::WEIGHT_PER_MILLIS, "Weight should be at most 50 ms.");
+		}
+	}
+}