Improve readability of ciphers/mixed_keyword_cypher.py (#8626)

* refactored the code

* the code will now pass the test

* looked more into it and fixed the logic

* made the code easier to read, added comments and fixed the logic

* got rid of redundant code + plaintext can contain chars that are not in the alphabet

* fixed the reduntant conversion of ascii_uppercase to a list

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

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* keyword and plaintext won't have default values

* ran the ruff command

* Update linear_discriminant_analysis.py and rsa_cipher.py (#8680)

* Update rsa_cipher.py by replacing %s with {}

* Update rsa_cipher.py

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

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* Update linear_discriminant_analysis.py

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

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* Update linear_discriminant_analysis.py

* Update linear_discriminant_analysis.py

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

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* Update linear_discriminant_analysis.py

* Update linear_discriminant_analysis.py

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

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* Update linear_discriminant_analysis.py

* Update machine_learning/linear_discriminant_analysis.py

Co-authored-by: Christian Clauss <[email protected]>

* Update linear_discriminant_analysis.py

* updated

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

* fixed some difficulties

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

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* added comments, made printing mapping optional, added 1 test

* shortened the line that was too long

* Update ciphers/mixed_keyword_cypher.py

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

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