Feature Request: A15 should keep root providers if MockBuilder is used with chains

[satanTime]

Describe the feature or problem you'd like to solve

Since Angular 15, many module providers become root providers and because there is not an easy way to detect which provider belongs to what module, quite often it can confuse.

For example, here: #4700

Proposed solution

NG_MOCKS_ROOT_PROVIDERS should be .keep if MockBuilder has been called with less than 2 parameters.