feat(protocol-kit): Add deployment functionality to Safe class

[DaniSomoza]

What it solves

Resolves #446

How this PR fixes it

• Removed the SafeFactory class
• created 2 private functions in the Safe class:
  • #addPreValidatedSignature: Adds a PreValidatedSignature to the transaction if the threshold is not reached.
  • #isReadyToExecute: Checks if the transaction has enough signatures to be executed.
• Added the deploy function in the Safe class.
• Added getSafeAddressFromDeploymentTx util function: Returns the address of a SafeProxy from the deployment tx receipt.

Previous PR reference

#905 #948