@table_from_file needs documenting and making more ergonomic

[evansd]

We may not love the API here, but it's already in use and requires ad-hoc explanation each time. See e.g.
https://bennettoxford.slack.com/archives/C01D7H9LYKB/p1724860666540569

Where the file being loaded has the structure given by another dataset definition we have the option of providing a much simpler API along the lines of:

new_table = table_from_file("path/to/file.arrow", other_dataset_definition.dataset)

i.e. we can use the existing dataset definition to provide the expected columns without needing to define them manually.

[evansd]

Another instance where we've had to explain this ad-hoc:
https://bennettoxford.slack.com/archives/C01D7H9LYKB/p1728384889288909