Contract should be a CrateType instead of a flag and specified in Nargo.toml

[phated]

Problem

Currently, contracts are only supported by some nargo commands and they require a special flag. This seems counter-intuitive because a contract package is always a contract package. This should be configured inside a Nargo.toml file instead and supported across all commands.

Happy Case

A crate can be configured as a "contract crate type" and all commands will use the logic to compile contracts.

Alternatives Considered

No response

Additional Context

No response

Would you like to submit a PR for this Issue?

Yes

Support Needs

No response

[phated]

Related to #1970