feat: Use ERC20 as native token on the stack

[jrchatruc]

What ❔

This PR aims to introduce an optional flag to the init command:

zk init --native-erc20

that will setup the stack using a custom ERC20 token as the native token of the L2.

Why ❔

Checklist

• [ ] PR title corresponds to the body of PR (we generate changelog entries from PRs).
• [ ] Tests for the changes have been added / updated.
• [ ] Documentation comments have been added / updated.
• [ ] Code has been formatted via zk fmt and zk lint.
• [ ] Spellcheck has been run via cargo spellcheck --cfg=./spellcheck/era.cfg --code 1.