Add Capability for CLI to Target Specific Contracts with a Flag

[0xNeshi]

It would make commands much faster and precise to execute if there was a something like a --contract flag, that would enable the Stylus CLI to perform operations on specific contracts instead of everything in a specific Cargo.toml.

By calling --contract "SomeContractName", the command could find that specific contract and check it or deploy it.
It should be able to handle inheritance correctly.

Example:

cargo stylus export-abi --contract Erc20