Add `@CheckReturnValue` and `@CanIgnoreReturnValue` to Mockito APIs

This would involve adding @CheckReturnValue to each package-info.java (or each class if there isn't a package-info.java), and also annotating a handful of APIs in the following classes with @CanIgnoreReturnValue (for APIs that return this).

• java/org/mockito/internal/creation/settings/CreationSettings.java
• java/org/mockito/junit/MockitoRule.java
• java/org/mockito/stubbing/BaseStubber.java
• java/org/mockito/internal/matchers/apachecommons/EqualsBuilder.java
• java/org/mockito/session/MockitoSessionBuilder.java
• java/org/mockito/internal/configuration/injection/MockInjection.java
• java/org/mockito/junit/VerificationCollector.java
• java/org/mockito/MockitoFramework.java
• java/org/mockito/stubbing/OngoingStubbing.java