Current benchmarking macro returns a closure with the captured
benchmarked code.
This can cause issues when the benchmarked code has complex lifetime
requirements.

This PR updates the existing macro by injecting the recording parameter
and invoking the start / stop method around the benchmarked block
instead of returning a closure

One other added benefit is that you can write this kind of code now as
well:

```rust
let v;
#[block]
{ v = func.call(); }
dbg!(v); // or assert something on v
```


[Weights compare
link](https://weights.tasty.limo/compare?unit=weight&ignore_errors=true&threshold=10&method=asymptotic&repo=polkadot-sdk&old=pg/fix-weights&new=pg/bench_update&path_pattern=substrate/frame/**/src/weights.rs,polkadot/runtime/*/src/weights/**/*.rs,polkadot/bridges/modules/*/src/weights.rs,cumulus/**/weights/*.rs,cumulus/**/weights/xcm/*.rs,cumulus/**/src/weights.rs)

---------

Co-authored-by: command-bot <>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@pari...>