[L2 Testnet Tutorial] L2 genesis and rollup configuration file creation

[sbvegan]

Description

The genesis and rollup configuration file creation needs to be updated to use the op-deployer tool. These file creations are touched on in three locations in the docs:

• https://docs.optimism.io/builders/chain-operators/tutorials/create-l2-rollup#generate-the-l2-config-files
• https://docs.optimism.io/builders/chain-operators/deploy/genesis
• https://docs.optimism.io/builders/chain-operators/tools/op-deployer#inspect-generate-genesis-files-and-chain-information

Acceptance criteria

• The docs mentioned in the description use the op-deployer method for creating the genesis and rollup config files

Resources and support

• The op-deployer docs are up to date

Action items

1. Update the OP Stack genesis creation documentation with the following changes:
   1. Update the warning callout to say, "The following genesis creation information is the legacy method for deploying the OP Stack L1 contracts. We do not recommend you use this method. They're left here for historical context." and move it to right above the Solidity script header
   2. Add the instructions included in the op-deployer documentation here
2. Update the L2 testnet tutorial - Generate the L2 config files with the steps from the op-deployer docs.

[krofax]

@sbvegan This is ready for review