PoV Reclaim Runtime Side (#3002)

# Runtime side for PoV Reclaim

## Implementation Overview
- Hostfunction to fetch the storage proof size has been added to the
PVF. It uses the size tracking recorder that was introduced in my
previous PR.
- Mechanisms to use the reclaim HostFunction have been introduced.
- 1. A SignedExtension that checks the node-reported proof size before
and after application of an extrinsic. Then it reclaims the difference.
- 2. A manual helper to make reclaiming easier when manual interaction
is required, for example in `on_idle` or other hooks.
- In order to utilize the manual reclaiming, I modified `WeightMeter` to
support the reduction of consumed weight, at least for storage proof
size.

## How to use
To enable the general functionality for a parachain:
1. Add the SignedExtension to your parachain runtime. 
2. Provide the HostFunction to the node
3. Enable proof recording during block import

## TODO
- [x] PRDoc

---------

Co-authored-by: Dmitry Markin <dmitry@markin.tech>
Co-authored-by: Davide Galassi <davxy@datawok.net>
Co-authored-by: Bastian Köcher <git@kchr.de>

cumulus/parachain-template/node/src/command.rs

@@ -1,5 +1,6 @@
 use std::net::SocketAddr;
 
+use cumulus_client_service::storage_proof_size::HostFunctions as ReclaimHostFunctions;
 use cumulus_primitives_core::ParaId;
 use frame_benchmarking_cli::{BenchmarkCmd, SUBSTRATE_REFERENCE_HARDWARE};
 use log::info;
@@ -183,7 +184,7 @@ pub fn run() -> Result<()> {
 			match cmd {
 				BenchmarkCmd::Pallet(cmd) =>
 					if cfg!(feature = "runtime-benchmarks") {
-						runner.sync_run(|config| cmd.run::<sp_runtime::traits::HashingFor<Block>, ()>(config))
+						runner.sync_run(|config| cmd.run::<sp_runtime::traits::HashingFor<Block>, ReclaimHostFunctions>(config))
 					} else {
 						Err("Benchmarking wasn't enabled when building the node. \
 					You can enable it with `--features runtime-benchmarks`."