Allow useOrderedRows to put all null elements at the bottom

[acelaya]

This PR changes useOrderedRows so that it can make null/undefined values be put always at the bottom of the list, and makes this the default behavior.

This is done by adding a new nullsLast option to the order object, which is true by default.

Callers will need to explicitly switch from nullsLast: true to nullsLast: false if they want this to change as the order direction changes:

const direction = 'descending';
const order = {
  field: 'display_name',
  direction,
  nullFirst: direction === 'descending',
}

Previously we were comparing nulls normally with other non-null values, which produced unintuitive results, because in JS both 'some string' > null and null > 'some string' are false.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (ea267fe) to head (0d300bc).

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1587   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           62        62           
  Lines         1041      1046    +5     
  Branches       397       402    +5     
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+ Hits          1041      1046    +5     

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[robertknight]

This implements what we discussed, but on reflection I wonder if perhaps it would be less surprising if we kept the hook stateless and instead gave the caller an option to determine whether null values sort before or after non-null values.

[robertknight]

Ah. My intention was that nulls would always sort either before or after non-null values. So we would never use </> comparisons between null and non-null values. I think it makes sense to default to true, assuming strings are the most common data type in rows and we'd probably want to sort them last.

[acelaya]

Done