Single DDS controller: `DDSControllerWidget`

[BECATRUE]

This closes #173.

I'm sorry that the updated code is too many. But, I think it is similar to that of DDS, so may be legible😅

For test, use the following code.

from PyQt5.QtWidgets import QApplication

from iquip.apps.monitor import DDSControllerWidget

qapp = QApplication([])
widget = DDSControllerWidget(
    name="DDS_test",
    device="urukul0",
    channel=0,
    frequencyInfo={
        "ndecimals": 3,
        "min": 1,
        "max": 400,
        "unit": "MHz",
        "step": 0.01
    }
)
widget.show()
qapp.exec_()

We can set the detailed options of frequency, amplitude, and phase spin box. I think it is okay to set the attenuation spin box to the fixed option, but if you think it is also necessary, I will update it.

Screenshot