cleanup chainspec value parsers

[mattsse]

atm the chainspec parsers are still in the utils crate

https://github.com/paradigmxyz/reth/blob/9c9b1fdf849992f0fa277e5135be3cbf8feb0139/crates/node/core/src/args/utils.rs#L27-L42

but they are no longer used in this crate. They should be moved to where the chainspec parsers are defined (chainspec crates).

we also need to rename:

https://github.com/paradigmxyz/reth/blob/9c9b1fdf849992f0fa277e5135be3cbf8feb0139/crates/node/core/src/args/utils.rs#L76-L76

to EthereumChainSpecParser