FEATURE add includes Eel Helpers for String and Array

[Kleisli]

resolved:https://github.com/neos/flow-development-collection/issues/2967 Added two new EelHelpers following the interface of the JavaScript functions String.prototype.includes() and Array.prototype.includes()

• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes
• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/includes

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Review instructions

Checklist

• [ ] Code follows the PSR-2 coding style
• [x] Tests have been created, run and adjusted as needed
• [x] The PR is created against the lowest maintained branch
• [x] Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• [x] Reviewer - The first section explains the change briefly for change-logs
• [ ] Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions

[mhsdesign]

FYI just made this wip because it has to land in 8.4 but were working on branching it of