sscanDevice: add select_channels() method

[prjemian]

Add similar to the ophyd.scaler.ScalerCH.select_channels() method.

[prjemian]

positioners

example code to implement for positioners

# scans.scan1.positioners.p1.setpoint_pv.value
# `xxx:m1.VAL`

scan = scans.scan1

positioners = []
for pname in scan.positioners.component_names:
    if len(getattr(scan.positioners, pname).setpoint_pv.value.strip()) > 0:
        positioners.append(pname)
scan.positioners.configuration_attrs = positioners
read_attrs = []
for pname in positioners:
    read_attrs.append(pname)
    for attr in getattr(scan.positioners, pname).component_names:
        # leave array out here (this is for interim reports)
        if attr == "array":
            continue
        read_attrs.append(f"{pname}.{attr}")
scan.positioners.read_attrs = read_attrs

[prjemian]

detectors

detectors = []
for dname in scan.detectors.component_names:
    if len(getattr(scan.detectors, dname).input_pv.value.strip()) > 0:
        detectors.append(dname)
scan.detectors.configuration_attrs = detectors
read_attrs = []
for dname in detectors:
    read_attrs.append(dname)
    for attr in getattr(scan.detectors, dname).component_names:
        # leave array out here (this is for interim reports)
        if attr == "array":
            continue
        read_attrs.append(f"{dname}.{attr}")
scan.detectors.read_attrs = read_attrs

[prjemian]

triggers

triggers = []
for tname in scan.triggers.component_names:
    if len(getattr(scan.triggers, tname).trigger_pv.value.strip()) > 0:
        triggers.append(tname)
scan.triggers.configuration_attrs = triggers
read_attrs = []
for dname in triggers:
    read_attrs.append(tname)
    for attr in getattr(scan.triggers, tname).component_names:
        # leave array out here (this is for interim reports)
        if attr == "array":
            continue
        read_attrs.append(f"{tname}.{attr}")
scan.triggers.read_attrs = read_attrs

[prjemian]

Note that in ScalerCH, kind is also configured:

        self.channels.kind = Kind.normal
        self.channels.read_attrs = list(read_attrs)
        self.channels.configuration_attrs = list(read_attrs)
        for ch in read_attrs[1:]:
            getattr(self.channels, ch).s.kind = Kind.hinted

Q: How does that apply here?