Use `.dataset` rather than `.field_time_serieses`?

[glwagner]

I'm wondering if we should replace "field_time_serieses" with "dataset" wherever it appears. I think "dataset" rolls of the tongue better and is also sufficiently distinct from data so that it won't be confused.

Also Oceananigans has a prototype "FieldDataset" designed to represent a group of FieldTimeSeries. It's not used much now, but could be developed further:

https://github.com/CliMA/Oceananigans.jl/blob/main/src/OutputReaders/field_dataset.jl

[adelinehillier]

That sounds like a good idea. "field_time_serieses" is a lot to type.