Added box examples in cpp and python

[ms-jagadeeshan]

🎉 New feature

• Part of Create examples for all classes #300

Summary

Added cpp and python example for Box class.

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.11%. Comparing base (91c73b9) to head (116dbd9).
Report is 7 commits behind head on gz-math7.

Additional details and impacted files

@@            Coverage Diff            @@
##           gz-math7     #584   +/-   ##
=========================================
  Coverage     94.11%   94.11%           
=========================================
  Files           146      146           
  Lines          9809     9809           
=========================================
  Hits           9232     9232           
  Misses          577      577           

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[ahcorde]

please in the cpp code include spaces in all operators and separators <<, =, ,, etc

[ms-jagadeeshan]

@ahcorde I have did the suggested changes.
Do we have cpplint(CPPLINT.CFG) and clang-tidy(.clang-tidy) config file for gazebo codestyle?
I code in neovim with language servers, formaters, linters enabled, which check for config file in
project root directory, if config file not found, then formats in default way(this mess the formatting), so i turned of my linters and formatters.
We should have linter and formatters config, may be in a gist or in every repo or somewhere else. So it could be downloaded and sym linked locally in project root, and code could be automatically formatted. What do you say?

[arjo129]

LGTM. Tested it works fine.

[arjo129]

@ahcorde can we proceed to merge this.