Rename Feature maps -> Encoding Circuits

[rothma]

Because it's the right thing to do

[rothma]

Proposals:

• encoding_circuits
• data_encoding_circuits. Nennen: dec
• ansatz

[rothma]

Final discussion with @David-Kreplin and then go to work

[rothma]

@David-Kreplin brought up a potential issue with non-x-dependent circuits --> pqc?

Also, let's change the name of the implemented feature maps to something meaningful (e.g. qek, param_z, highdim?)

[JanSchnabel]

But the same would hold for only-x-depending circuits. Okay, then x can be viewed as parameter and therefore pqc would be fine. What about something even more general like SqulearnCircuits as analogue to Qiskit's QuantumCircuit?

[MoritzWillmann]

@David-Kreplin brought up a potential issue with non-x-dependent circuits --> pqc?

Does this UC exist? I'd be fine with pqc aswell, though.

But the same would hold for only-x-depending circuits. Okay, then x can be viewed as parameter and therefore pqc would be fine. What about something even more general like SqulearnCircuits as analogue to Qiskit's QuantumCircuit?

I'm not sure if we should come up with something that isn't really meaningful. Just calling it Circuit or QuantumCircuit might work though.

[JanSchnabel]

There is also the proposal "Ansatz" in one of the comments above -> AnsatzCircuit would be another suggestion to be more different from Qiskit

[rothma]

Since data encoding circuits will be the default case, I would prefer to keep it as a name. My suggestion would be to rename the feature_maps_implemented to data encoding circuits and maybe rename the parent folder to circuits or something along these lines.

[David-Kreplin]

Closed with PR #159