added smith waterman algorithm (#9001)

* added smith waterman algorithm

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* descriptive names for the parameters a and b

* doctesting lowercase upcase empty string cases

* updated block quot,fixed traceback and doctests

* shorter block quote

Co-authored-by: Tianyi Zheng <[email protected]>

* global vars to func params,more doctests

* updated doctests

* user access to SW params

* formating

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Tianyi Zheng <[email protected]>