Added 8 more grouping tests and improved existing grouping tests.
Added 8 more grouping tests and improved existing grouping tests.

NightOwl888/lucenenet,jeme/lucenenet,NightOwl888/lucenenet,jeme/lucenenet,NightOwl888/lucenenet,apache/lucenenet,apache/lucenenet,jeme/lucenenet,apache/lucenenet,apache/lucenenet,NightOwl888/lucenenet,jeme/lucenenet