tracking.singleaxis takes apparent_azimuth

[AdamRJensen]

The pvlib.tracking.singleaxis takes input parameters of apparent_zenith and apparent_azimuth. Since the solar azimuth angle is not affected by refraction, this parameter name does not make sense. It is the only place in pvlib that apparent_azimuth is used.

https://github.com/pvlib/pvlib-python/blob/a27c68689516eb0520d30db33957815ba9398663/pvlib/tracking.py#L9-L11

This discussion is related to #1403.

A number of attendees at the 2025 PVSC pvlib tutorial had issues finding the apparent_azimuth parameter (for good reason), hence I think the inputs should be changed to solar_, which would also be consistent with most other pvlib functions (even when they require apparent solar angles).