[Test Framework] Add helper function for contract deployment

[SupunS]

Work towards https://github.com/onflow/cadence/issues/331

Description

Introduced a utility function to deploy a contract to the blockchain.

let err = blockchain.deployContract(
    contractName,
    contractCode,
    authorizerAddress,
    signers,
    contractInitArgs,
)

Devs can also deploy contracts using a transaction. This is a utility method that does the same under the hood.

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• [ ] Targeted PR against master branch
• [x] Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• [x] Code follows the standards mentioned here
• [x] Updated relevant documentation
• [x] Re-reviewed Files changed in the Github PR explorer
• [x] Added appropriate labels