feat(config): Add support for nested chain config override

[antiyro]

Right now I am only able to use --chain-config-override for the parent fields of the chain config like:

 --chain-config-override sequencer_address=0x123

I would like to be able to modify nested fields in order for exemple to modify the steps number of the chain config like:

--chain-config-override bouncer_config.block_max_capacity.n_steps=100000

It apears that this function does not support it