Specifying host.json options on a per function level

#### Is your question related to a specific version? If so, please specify:
v3 runtime

#### What language does your question apply to? (e.g. C#, JavaScript, Java, All)
C#

#### Question
I am trying to specify `queues` -> `batchSize` on a per function basis. It seems like I should be able to do this. Right now, it looks like my only option is to create a separate Azure Functions instance/project for each function that I want to take a different configuration.

Start by reviewing the v3 runtime's handling of host.json and the queues -> batchSize setting for C# functions. Determine whether configuration can be scoped to an individual function and what syntax would express it; done requires a confirmed answer or an agreed implementation path for per-function settings.

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