Balances: Configurable Number of Genesis Accounts with Specified Balances for Benchmarking (#6267)

# Derived Dev Accounts

Resolves https://github.com/paritytech/polkadot-sdk/issues/6040

## Description
This update introduces support for creating an arbitrary number of
developer accounts at the genesis block based on a specified derivation
path. This functionality is gated by the runtime-benchmarks feature,
ensuring it is only enabled during benchmarking scenarios.

### Key Features
- Arbitrary Dev Accounts at Genesis: Developers can now specify any
number of accounts to be generated at genesis using a hard derivation
path.

- Default Derivation Path: If no derivation path is provided (i.e., when
`Option<dev_accounts: (..., None)>` is set to `Some` at genesis), the
system will default to the path `//Sender//{}`.

- No Impact on Total Token Issuance: Developer accounts are excluded
from the total issuance of the token supply at genesis, ensuring they do
not affect the overall balance or token distribution.

polkadot address: 14SRqZTC1d8rfxL8W1tBTnfUBPU23ACFVPzp61FyGf4ftUFg

---------

Co-authored-by: Sebastian Kunert <skunert49@gmail.com>