feat: add row echelon matrix algorithm

[piyushk77]

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Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new JavaScript files are placed inside an existing directory.
• All filenames should use the UpperCamelCase (PascalCase) style. There should be no spaces in filenames.
  Example:UserProfile.js is allowed but userprofile.js,Userprofile.js,user-Profile.js,userProfile.js are not
• All new algorithms have a URL in their comments that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[appgurueu]

The decomposition into a set of properly named small functions makes this reasonably readable even without comments everywhere, though I suppose some comments wouldn't hurt. The doc comment needs to be moved to the proper function though, and the error case should throw. formatResult should be removed in favor of just using float tolerance in testing.

[piyushk77]

@appgurueu I have made the modifications. Have removed the formatResult and replaced it with isTolerant. Have changed the error cases to use throw instead of return. Also added the necessary comments wherever required.