Port usage of add_submodule to assign to an attribute

Nobody has claimed this yet.

Now that add_submodule returns the newly created submodule we should update all instrument drivers in src/qcodes/instrument_drivers to make use of this.

This means that as an example a line like

```
self.add_submodule("correction", KeysightB1500Correction(self, "correction"))
```

should be replaced by

```
self.correction: KeysightB1500Correction = self.add_submodule("correction", KeysightB1500Correction(self, "correction"))
"""
Instrument module correction
"""
```

e.g the attribute should be assigned to the same value as the name argument, the type should be included and a docstring added after the attribute.

In the first round we should only do this for attributes where the name can be known statically and not try to do this when the name is dynamically created. E.g. We want to avoid using `__setattr__`

Search the usages of add_submodule under src/qcodes/instrument_drivers and identify calls whose name argument is statically known. Update those attributes to assign the returned submodule with the matching type and add the requested docstring, while leaving dynamically named cases unchanged. Done means all eligible instrument-driver usages follow the documented pattern.

Written by the indexing model from the issue text.