Allow frequency domain driven simulations at list of desired frequency samples

[sebastiangrimberg]

In addition to the linear frequency sweep currently implemented, configured with "MinFreq", "MaxFreq", and "FreqStep", allow user to override with a list of frequencies, perhaps using the "FreqSamples" keyword. This is incompatible with adaptive fast frequency sweep.

[WEIXUEP]

Hi @sebastiangrimberg , I believe that the Advanced Design System (ADS) by Keysight can serve as a valuable reference.

In my code, I run palace multiple times (from python) and combine the results of different frequency range. This only requires packaging of the code, without changing the core algorithm.

`Freq1 = {"Type": "Adaptive",
"MinFreq": 1.8,
"MaxFreq": 2.2,
"FreqStep": 0.05}

Freq2 = {"Type": "Linear",
"MinFreq": 1.0,
"MaxFreq": 1.2,
"FreqStep": 0.1}

user_config_data["Freq"].append(Freq1)
user_config_data["Freq"].append(Freq2)`