Add overhead benchmark to frame-omni-bencher (#5891)

# Benchmark Overhead Command for Parachains

This implements the `benchmark overhead` command for parachains. Full
context is available at:
https://github.com/paritytech/polkadot-sdk/issues/5303. Previous attempt
was this https://github.com/paritytech/polkadot-sdk/pull/5283, but here
we have integration into frame-omni-bencher and improved tooling.

## Changes Overview

Users are now able to use `frame-omni-bencher` to generate
`extrinsic_weight.rs` and `block_weight.rs` files for their runtime. The
core logic for generating these remains untouched; this PR provides
mostly machinery to make it work for parachains at all.

Similar to the pallet benchmarks, we gain the option to benchmark based
on just a runtime:

```
frame-omni-bencher v1 benchmark overhead --runtime {{runtime}}
```

or with a spec:

```
frame-omni-bencher v1 benchmark overhead --chain {{spec}} --genesis-builder spec
```

In this case, the genesis state is generated from the runtime pres...