improve the error message for missing zk compiler output

[tmrtx]

Command:

zkforge zk-create src/Counter.sol:Counter --chain 280 --rpc-url https://zksync2-testnet.zksync.dev:443 --private-key "PK"

Before:

The application panicked (crashed).
Message:  Unable to read file: Os { code: 2, kind: NotFound, message: "No such file or directory" }
Location: cli/src/cmd/forge/zk_create.rs:324

After:

The application panicked (crashed).
Message:  Unable to read contract output file at /onchain/hello-world/zkout/Counter.sol/artifacts.json: Os { code: 2, kind: NotFound, message: "No such file or directory" }
Location: cli/src/cmd/forge/zk_create.rs:325

[sammyshakes]

looks good. thanks

[berryhill]

@tmrtx first official open source PR, thank you!

[tmrtx]

@tmrtx first official open source PR, thank you!

thanks @berryhill!