Fix/Add all MW channel properties

[nulinspiratie]

This PR adds the following changes

• Add missing attributes to MWChannel
• Make Channel an abstract base class
• Move intermediate_frequency to Channel, meaning that all channels share this property
• Add smearing, time_of_flight

[deanpoulos]

Hey Serwan, the attributes look good, but it looks like the MWChannel is missing the API for creating QUA commands, e.g.,

AttributeError: 'InOutMWChannel' object has no attribute 'measure'

These currently live in e.g., the IQChannel class. Perhaps you could put a separate class which contains just the interface for creating QUA command and have both InOutIQchannel and InOutMWChannel inherit from this.

[deanpoulos]

Another thing is that it wont allow you to add IQ waveforms unless it is an IQChannel, but you should also be able to add IQWaveforms to an MWChannel. So in
quam/components/pulses.py, you could add something like:

                 channel type (SingleChannel, IQChannel, InOutIQChannel).
         """
 
-        from quam.components.channels import SingleChannel, IQChannel
+        from quam.components.channels import SingleChannel, IQChannel, MWChannel
 
         pulse_config = config["pulses"][self.pulse_name]
 
@@ -221,7 +221,7 @@ class Pulse(QuamComponent):
                 "Waveform type 'single' not allowed for IQChannel"
                 f" '{self.channel.name}'"
             )
-        elif "I" in waveforms and not isinstance(self.channel, IQChannel):
+        elif "I" in waveforms and not isinstance(self.channel, (IQChannel, MWChannel)):
             raise ValueError(
                 "Waveform type 'IQ' not allowed for SingleChannel"
                 f" '{self.channel.name}'"

[nulinspiratie]

Addressed both issues, @deanpoulos wdyt?