Add go-deepcopy

[tiendc]

Add go-deepcopy

Please provide package links to:

• repo link (github.com, gitlab.com, etc): https://github.com/tiendc/go-deepcopy
• pkg.go.dev: https://pkg.go.dev/github.com/tiendc/go-deepcopy
• goreportcard.com: https://goreportcard.com/report/github.com/tiendc/go-deepcopy
• coverage service link (codecov, coveralls, etc.): https://codecov.io/gh/tiendc/go-deepcopy

Checklist:

• The package has been added to the list in alphabetical order.
• The package has an appropriate description with correct grammar.
• As far as I know, the package has not been listed here before.
• The repo documentation has a pkg.go.dev link.
• The repo documentation has a coverage service link.
• The repo documentation has a goreportcard link.
• The repo has a version-numbered release and a go.mod file.
• I have read the Contribution Guidelines, Maintainers Note and Quality Standards.
• The repo has a continuous integration process that automatically runs tests that must pass before new pull requests are merged.
• The authors of the project do not commit directly to the repo, but rather use pull requests that run the continuous-integration process.

Thanks for your PR, you're awesome! 👍