Refactor KMP and RabinKarp: Improve Reusability and Test Coverage (#7250)

* first commit

* Running KMPTest and RabinKarpTest with fixed formatting

* now build failed error resolved

* now build failed error resolved 2

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Co-authored-by: Divyansh Saxena <divyanshsaxena@gmail.com>
Co-authored-by: Deniz Altunkapan <deniz.altunkapan@outlook.com>