Add index as argument to createValidator

[monrus]

Hi, this pull request allows use index of a current array element for compare with other fields of object in the array.

Example:

'stepTimeIntervals[].to': composeValidators(
    isRequired,
    createValidator(
      message => (value, allValues, idx) => {
        if (!allValues.stepTimeIntervals[idx] || value < allValues.stepTimeIntervals[idx].from) {
          return message
        }
      },
      field => `${field} must be more than from`
      )
  )('')

TODO:
Checking use cases coverage and add tests

[codecov-io]

Codecov Report

Merging #62 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #62   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          30     30           
  Lines         225    225           
  Branches       62     62           
=====================================
  Hits          225    225

Impacted Files	Coverage Δ
src/internal/internalCombineValidators.js	100% <100%> (ø)	⬆️
src/internal/createValidatorWithSingleError.js	100% <100%> (ø)	⬆️
src/createValidator.js	100% <100%> (ø)	⬆️

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