Implement contains for exact matches of subportions of a string. Using the Knuth–Morris–Pratt algorithm, we should be able to do this in a linear runtime with a tiny bit of preprocessing at the invocation.

Reporter: Uwe Korn / @xhochy
Assignee: Uwe Korn / @xhochy

Related issues:

• [C++] Add substring count kernel (relates to)
• [C++] Add string starts-with/ends-with kernels (is related to)

PRs and other links:

• GitHub Pull Request #7593

_{Note: This issue was originally created as ARROW-9160. Please see the migration documentation for further details.}