Is your feature request related to a problem? Please describe.
Using the Cosmos 4.0 SDK, RetryOptions are parameters are required fields

Describe the solution you'd like
Change interface from:

maxRetryAttemptCount: number;
fixedRetryIntervalInMilliseconds: number;
maxWaitTimeInSeconds: number;

To

maxRetryAttemptCount?: number;
fixedRetryIntervalInMilliseconds?: number;
maxWaitTimeInSeconds?: number;

And merge the input with the defaults so that any undefined parameters are set with the defaults.

Describe alternatives you've considered
Just define everything with the default values. (Also an issue because the default value for fixedRetryIntervalInMilliseconds isn't clearly defined in the documentation