New Function Added To Get Columns From Files

[iquevedo123]

New function added to get all columns from each csv provided. Function can also find common columns (those that appear more than once across your csv's). Documentation written up, GitHub site updated, News page updated, checks applied, and lintr checks ran. No unit tests written (not too well-versed in writing unit tests).

[RobLBaker]

Thanks Issac! I may not be able to review this until after the upcoming Botany meetings (so late June). Sorry for the delay.

[RobLBaker]

I'm wondering if this should be called get_column_names() rather than get_columns_from_files() as I think it returns the column names, not the columns themselves (and update associated documentation to clarify this point)

[RobLBaker]

Can this all be updated to something like "get_column_names" or "get_column_headers"? The function doesn't actually return the columns themselves, so the name "get_columns_from_files" is a bit misleading/confusing.