Fix using js-joda getDiff with LocalDates and time intervals

[joshkel]

As needed by, e.g., MUI's DatePicker:

https://github.com/mui/mui-x/blob/d8b76d392976d8c1c9eeeb37d13a6d2368751f9a/packages/x-date-pickers/src/internals/hooks/useMaskedInput.tsx#L100

[codecov-commenter]

Codecov Report

Merging #634 (610310f) into master (6c16bac) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 610310f differs from pull request most recent head 3a5be3c. Consider uploading reports for the commit 3a5be3c to get more accurate results

@@            Coverage Diff            @@
##            master      #634   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           16        16           
  Lines         1539      1543    +4     
  Branches       196       197    +1     
=========================================
+ Hits          1539      1543    +4     

Impacted Files	Coverage Δ
packages/js-joda/src/js-joda-utils.ts	100.00% <100.00%> (ø)

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