Remove spread operator in object diffs to increase performance

[SheneekaW]

Motivation and Context

While using detailedDiff from this library, ran into an issue where large enough files would cause functions to just hang. After updating the object value assignments and removing the spread operator (...), the performance improved.

**Note did not remove the spread operator from the array function or smaller utility functions.

Relied on the following functions for timing and heap usage:

console.time()
console.timeEnd()
process.memoryUsage()

How Has This Been Tested?

While making changes, made sure test suite was still good with npm test runs

[coveralls]

Coverage remained the same at 100.0% when pulling 3c6c607 on SheneekaW:remove-spread-op into 6296889 on mattphillips:master.

[anko]

Possibly equivalent to #47? It was closed for some reason.

[codecov-commenter]

Codecov Report

Merging #64 (70aa278) into main (8c09976) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 70aa278 differs from pull request most recent head 1d430f4. Consider uploading reports for the commit 1d430f4 to get more accurate results

@@            Coverage Diff            @@
##              main       #64   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            7         7           
  Lines           99       109   +10     
  Branches        36        36           
=========================================
+ Hits            99       109   +10     

Impacted Files	Coverage Δ
src/added.js	100.00% <100.00%> (ø)
src/deleted.js	100.00% <100.00%> (ø)
src/diff.js	100.00% <100.00%> (ø)
src/updated.js	100.00% <100.00%> (ø)

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[mattphillips]

Thanks @SheneekaW will get this published ASAP