Add missing type definitions + rename sortFn

[jshjohnson]

Description

• Update types file
• Utilised type defs throughout
• Minor refactoring
• Renames sortFn to sorter to be consistent with other functions passed via config
• Renames itemComparer to valueComparer to be clearer about what the function actually does

Screenshots (if appropriate)

Types of changes

• Chore (tooling change or documentation change)
• Refactor (non-breaking change which maintains existing functionality)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[codecov]

Codecov Report

Merging #734 into master will increase coverage by 0.28%.
The diff coverage is 74.5%.

@@            Coverage Diff             @@
##           master     #734      +/-   ##
==========================================
+ Coverage   66.18%   66.46%   +0.28%     
==========================================
  Files          23       22       -1     
  Lines        1307     1309       +2     
==========================================
+ Hits          865      870       +5     
+ Misses        442      439       -3

Impacted Files	Coverage Δ
src/scripts/components/wrapped-input.js	100% <ø> (ø)	⬆️
src/scripts/actions/items.js	100% <ø> (ø)	⬆️
src/scripts/components/wrapped-select.js	100% <ø> (ø)	⬆️
src/scripts/components/input.js	100% <ø> (ø)	⬆️
src/scripts/actions/choices.js	100% <ø> (ø)	⬆️
src/scripts/actions/groups.js	100% <100%> (ø)	⬆️
src/scripts/components/dropdown.js	100% <100%> (ø)	⬆️
src/scripts/lib/utils.js	74.24% <100%> (ø)	⬆️
src/scripts/actions/misc.js	100% <100%> (ø)	⬆️
src/scripts/store/store.js	92% <100%> (-1.34%)	⬇️
... and 5 more

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[tinovyatkin]

@jshjohnson can we rename sortFn to sortProvider? My breaking PR is to introduce searchProvider and make it easy to build autocomplete on top of Choices

And also removing completely all sort related settings - I mean, if sortProvider is set, then it makes all the rest of decisions.

I would like to do similar approach to searchProvider - it will allow us to decouple fuse.js and bunch of settings we are having around it now.

[tinovyatkin]

That's also can be done in a way of deprecation - I mean, undocument old settings now, but still support it until next major.

[tinovyatkin]

BTW, my searchProvider will be supporting promises (similar to setChoices approach), not sure if that makes sense for sorting, but...

[jshjohnson]

BTW, my searchProvider will be supporting promises (similar to setChoices approach), not sure if that makes sense for sorting, but...

Hmm, hard to say without seeing your implementation. Do you mind if I keep this as is for the time being and if we think we need to update it after your search PR, we can?