Does ECCOMetadata have dates or a date? (Should we use a different design for ECCOMetadata?)

[glwagner]

The docstring says date

ClimaOcean.jl/src/DataWrangling/ECCO/ECCO_metadata.jl

Line 54 in 9c858b0

- `date`: The date of the metadata (default: DateTimeProlepticGregorian(1993, 1, 1)).

but the actual function signature requires dates:

ClimaOcean.jl/src/DataWrangling/ECCO/ECCO_metadata.jl

Line 59 in 9c858b0

dates = DateTimeProlepticGregorian(1993, 1, 1),

I also want to note that I think this design is confusing. The user interface is confusing, and it also makes the source code confusing.

Another design could be to have ECCOMetadata represent a single instance and then use a vector of ECCOMetadata to represent many of them (if that is even necessary).

Anything to make the design more explicit with less hidden suprises.

[glwagner]

I guess another possibility is to discontinue "single date" support, so users just have to write [date] if they want one date.