8.13.10 lacks UpdateMany<TSource, TPartialDocument>

[gkores]

Is your feature request related to a problem? Please describe.
I am porting some NEST code to the newer 8.x client and have encountered an issue where in NEST i can call UpdateMany<TSource, TPartialDocument> while this isn't available in the newer client. This makes partial updates of multiple documents harder than it should have to be. Update<TSource, TPartialDocument> is available in 8.x, so I believe the same should be true for UpdateMany.

Describe the solution you'd like
UpdateMany<TSource, TPartialDocument> is available in 8.x

Describe alternatives you've considered
UpdateMany with a script might be possible, but UpdateMany<TSource, TPartialDocument> would be cleaner.