Create superdense_coding.py

[KevinJoven11]

Describe your change:

Add quantum superdense coding algorithm. The principal idea is to send two classical bits in to one quantum bit (qubit.)

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

Checklist:

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized.
• [x] I know that pull requests will not be merged if they fail the automated tests.
• [x] This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• [x] All new Python files are placed inside an existing directory.
• [x] All filenames are in all lowercase characters with no spaces or dashes.
• [x] All functions and variable names follow Python naming conventions.
• [x] All function parameters and return values are annotated with Python type hints.
• [x] All functions have doctests that pass the automated testing.
• [x] All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• [x] If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[KevinJoven11]

Dear @cclauss, This is the final contribution required for the #Hacktoberfest. Thanks for your comments and help. I really appreciate your time. Let me know if everything works well. Best,

[CaedenPH]

@prateekiiest I had made a pretty important comment that qasm_simulator is deprecated, so this algorithm will raise warnings and someone will need to fix this

[prateekiiest]

@CaedenPH made a revert PR. sorry for missing that

[prateekiiest]

Closing as per PR comments. Thanks