Contracts: Rework host fn benchmarks (#4233)

fix https://github.com/paritytech/polkadot-sdk/issues/4163

This PR does the following:
Update to pallet-contracts-proc-macro: 
- Parse #[cfg] so we can add a dummy noop host function for benchmark.
- Generate BenchEnv::<host_fn> so we can call host functions directly in
the benchmark.
- Add the weight of the noop host function before calling the host
function itself

Update benchmarks:
- Update all host function benchmark, a host function benchmark now
simply call the host function, instead of invoking the function n times
from within a contract.
- Refactor RuntimeCosts & Schedule, for most host functions, we can now
use the generated weight function directly instead of computing the diff
with the cost! macro

```rust
// Before
#[benchmark(pov_mode = Measured)]
fn seal_input(r: Linear<0, API_BENCHMARK_RUNS>) {
    let code = WasmModule::<T>::from(ModuleDefinition {
        memory: Some(ImportedMemory::max::<T>()),
        imported_functions: vec![ImportedFunction {
            module: "seal0",
            name: "seal_input",
            params: vec![ValueType::I32, ValueType::I32],
            return_type: None,
        }],
        data_segments: vec![DataSegment { offset: 0, value: 0u32.to_le_bytes().to_vec() }],
        call_body: Some(body::repeated(
            r,
            &[
                Instruction::I32Const(4), // ptr where to store output
                Instruction::I32Const(0), // ptr to length
                Instruction::Call(0),
            ],
        )),
        ..Default::default()
    });

    call_builder!(func, code);

    let res;
    #[block]
    {
        res = func.call();
    }
    assert_eq!(res.did_revert(), false);
}
```

```rust
// After
fn seal_input(n: Linear<0, { code::max_pages::<T>() * 64 * 1024 - 4 }>) {
    let mut setup = CallSetup::<T>::default();
    let (mut ext, _) = setup.ext();
    let mut runtime = crate::wasm::Runtime::new(&mut ext, vec![42u8; n as usize]);
    let mut memory = memory!(n.to_le_bytes(), vec![0u8; n as usize],);
    let result;
    #[block]
    {
        result = BenchEnv::seal0_input(&mut runtime, &mut memory, 4, 0)
    }
    assert_ok!(result);
    assert_eq!(&memory[4..], &vec![42u8; n as usize]);
}
``` 

[Weights
compare](https://weights.tasty.limo/compare?unit=weight&ignore_errors=true&threshold=10&method=asymptotic&repo=polkadot-sdk&old=master&new=pg%2Frework-host-benchs&path_pattern=substrate%2Fframe%2Fcontracts%2Fsrc%2Fweights.rs%2Cpolkadot%2Fruntime%2F*%2Fsrc%2Fweights%2F**%2F*.rs%2Cpolkadot%2Fbridges%2Fmodules%2F*%2Fsrc%2Fweights.rs%2Ccumulus%2F**%2Fweights%2F*.rs%2Ccumulus%2F**%2Fweights%2Fxcm%2F*.rs%2Ccumulus%2F**%2Fsrc%2Fweights.rs)

---------

Co-authored-by: command-bot <>
Co-authored-by: Alexander Theißen <[email protected]>