Add simple default filter options function

[joeyparis]

Currently, if you set the search prop to true but do not provide a filterOptions function then the entire options list is always returned. I added a simple default filter function that checks if the search value is included (case insensitive) anywhere in the name value of each option.

Alternatively, we could log an error/warning if search is true but filterOptions is null.

[vercel]

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🔍 Inspect: https://vercel.com/tbleckert/react-select-search/E624VfFZQWGrJQDNXqZP44oDLzkt
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