Hedging: Adds support for writes on multi region accounts

[NaluTripician]

Pull Request Template

Description

Adds support to use hedging on write requests for multimaster accounts. Note that this does come with the caveat that there will be more 409 errors thrown by the SDK. This is expected and applications that adapt this feature should be prepared to handle these exceptions.

This feature will also be an opt in feature for Availability Strategies and users will need to explicitly specify that in the availability strategy definition.

ItemRequestOptions requestOptions = new ItemRequestOptions
{
    AvailabilityStrategy = new CrossRegionHedgingAvailabilityStrategy(
        threshold: TimeSpan.FromMilliseconds(100),
        thresholdStep: TimeSpan.FromMilliseconds(50),
        multiMasterWritesEnabled: true)
};

Type of change

Please delete options that are not relevant.

• [] New feature (non-breaking change which adds functionality)

Closing issues

To automatically close an issue: closes #4457

[github-actions]

All good!

[Pilchie]

The feature is not named "multi-master", right? We call it multiple write regions, or active-active in docs. We should change the API to match.