Circuit composition wraps per default

[Cryoris]

Summary

Add a wrap keyword argument to QuantumCircuit.compose to set whether the composed circuit should be wrapped in an instruction or not.

Per default, wrap the other circuit, to allow a better overview of the individual circuit blocks (especially if attaching library circuits) and be closer to the behavior of append so that in long-term we can remove that one and keep only compose. Note that this changes how the default of how circuit.compose(other) looks like, but it's no functional change.

Closes #6147 (but does a bit more, see also the discussion in that issue).

Details and comments

• compose get's a new wrap argument that's True by default
• append also get's a front argument to append infront of a circuit to streamline the usage with compose (but mainly to simplify the logic in the code)
• the library circuits QuantumVolume, Permute and IQP don't return a circuit with a single wrapped instruction, since compose now wraps and to improve consistency with the rest of the library

[Cryoris]

@jaygambetta (I need a message to send you a link to the code)

[jaygambetta]

thanks looking forward to seeing this but if we dont wrap by default this does not close the issue we need a second pr for the libraries.

[Cryoris]

yes, I'll refactor this one and open a new one for wrapping the library circuits 👍🏻

[Cryoris]

Closing in favor of #6634 and #6659.