fix: support async vector search from a collection #949

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@NickChittle

The following contributors were found for this pull request:

✅ 8e3bd1d Author: @NickChittle <ni*****le@gmail.com>
✅ 6f86506 Author: @parthea <par*****ou@google.com>
✅ d4956f4 Author: @renovate-bot <b**@renovateapp.com>
✅ d4956f4 Co-Author: @gcf-owl-bot[bot] <gcf-owl-bot[bot]@users.noreply.github.com>
✅ d4956f4 Co-Author: <sa***e@google.com>

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