Fix circular dependencies in @azure/cosmos

[joheredi]

There are 2 circular dependency problems

RequestHandler -> RetryUtility -> RequestHandler

Problem: RequestHandler.execute calls retryUtitlity.execute to retry the request if there is an error. However RetryUtility.execute calls RequestHandler.executeRequest causing the circular dependency

There are a few options to fix this:
a) Move retryUtility.execute to RequestHandler
b) Have pass executeRequest to retryUtility.execute as a parameter
c) Move executeRequest to retryUtility

I think option (b) would be preferable because it would provide flexibility of passing any other request to be retried if needed, without a hard dependency on RequestHandler

@ramya-rao-a , @southpolesteve, @HarshaNalluru - What do you think? Do you have any other options in mind?

HeaderUtils -> QueryMetrics -> ClientSideMetrics -> HeaderUtils

Problem: headerUtils.getInitialHeader uses queryMetrics.zero which also clientSideMetrics.zero. Since clientSideMetrics.add uses headerUtils.getRequestChargeIfAny.

headerUtils.getRequestChargeIfAny returns headers as is if it is a number

Since clientSideMetrics.requestCharge is always a number, we don't really need to call headerUtils.getRequestChargeIfAny, we can just use clientSideMetrics.requestCharge directly.

Fixes #5255

[southpolesteve]

I fine with the solution 1.b. Makes sense to me. That retry code is a bit nutty, but it is not worth doing some big refactor now.

For 2. Even though the type says it is a number, I don't think you can trust it. You'll need to add a Number() wrapper over here to make sure. The index type of CosmosHeaders is [key: string]: string | boolean | number which is not great. I think it is like that because we use it for both request and response headers. Again. Problematic, but probably not worth a big refactor right now.