Add tooltip to "Invert Polarity" checkbox

[cjsha]

I think it's potentially unclear why someone would want to invert polarity even though it's the recommended setting (and thus why the checkbox is checked by default when the GUI is opened). I think this because I'm not sure it's common knowledge that the raw data from the Neuropixels hardware is inverted. In particular, I expect users will see the checkbox and think "I don't want to invert my data, that's going to make my spikes upside down and add an additional pre-processing step of un-inverting my data to perform spike sorting" or something like that. I'm pretty sure other software don't expose this option to users so won't an a priori understanding of why the checkbox is there.

Of course, this checkbox is explained here in our docs, but I don't think the user should necessarily have to navigate to the website to figure out what's going on in this case. Therefore, I propose adding a tooltip that says something similar to the explanation in our docs.

I will initially place this in 0.6.1, but this issue may be dropped or moved per discussions in our issue-sorting meetings.

[bparks13]

Closing this issue, as the associated PR has been closed, and we will not be pursuing this further.