refactor: selected option typing

[MykhailoButkevych-MR]

1. Fix as ts definitions for selected option.
2. Add selectedOptionResolver helper function.
3. Remove searchable prop from Select childs, instead it can be verified based on searchValue.
4. searchValue can be null which means Select isn't searchable.
5. Change prop name selectedOption to selectedOptions for MultiSelect

[changeset-bot[bot]]

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Latest commit: 62e57cb8f8cbadfee286cee657d3648e03a46108

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