Type error in searchOptions["facets"] which should also accept `string`

The current type of `facets` in the searchOptions is:

https://github.com/algolia/algoliasearch-client-javascript/blob/ba59b68aa9494c29e284ed45e924267d7388baa9/packages/client-search/src/types/SearchOptions.ts#L104

Nonetheless, while this is true when no facets are checked, once it is `facets` may contain a string.

Open packages/client-search/src/types/SearchOptions.ts at the linked line and inspect the current type definition for searchOptions["facets"]. Confirm how the type represents facets when values are selected, then update the declaration so string values are accepted while preserving the existing forms; the work is done when the reported TypeScript error no longer occurs.

索引モデルが issue の本文から書いたものです。