Switch to Hardhat configuration variables instead of using `.env`

[andrejrakic]

Update the project to support Hardhat configuration variables instead of using .env file(s)

[zeuslawyer]

@andrejrakic Wondering if there is any advantage to this since the vars are stored as plain tex, just the same as .env files?

Would using hardhat var offer any significant advantage to the developer, their learning or experience? or will it simply nudge developers towards switching from a workflow (.env files) they are already familiar with? We have observed that env-enc created the same "friction" given that devs were accustomed to .env files (even though env-enc had WAY more protection in the form of encryption).