Enable controlled initialization: derive Initialize from Gate

[Cryoris]

What is the expected behavior?

Initialize is currently derived from Instruction as it contains resets. As such we cannot do controlled initialization or use any other Gate method. There should be an option to turn the resets off and obtain a Gate instance to create controlled initializations. Resetting the qubits accordingly is left to the user in that case.

[Cryoris]

Note: One can use an isometry instruction to do this.