C#: Add cs/dereferenced-value-is-always-null and cs/dereferenced-value-may-be-null to the Code Quality suites.

Author: michaelnebel

csharp/ql/integration-tests/posix/query-suite/csharp-code-quality.qls.expected

@@ -2,6 +2,8 @@ ql/csharp/ql/src/API Abuse/CallToGCCollect.ql
 ql/csharp/ql/src/API Abuse/FormatInvalid.ql
 ql/csharp/ql/src/API Abuse/NoDisposeCallOnLocalIDisposable.ql
 ql/csharp/ql/src/Bad Practices/Control-Flow/ConstantCondition.ql
+ql/csharp/ql/src/CSI/NullAlways.ql
+ql/csharp/ql/src/CSI/NullMaybe.ql
 ql/csharp/ql/src/Dead Code/DeadStoreOfLocal.ql
 ql/csharp/ql/src/Language Abuse/MissedReadonlyOpportunity.ql
 ql/csharp/ql/src/Likely Bugs/Collections/ContainerLengthCmpOffByOne.ql

csharp/ql/src/CSI/NullAlways.ql

@@ -9,6 +9,7 @@
  *       correctness
  *       exceptions
  *       external/cwe/cwe-476
+ *       quality
  */
 
 import csharp

csharp/ql/src/CSI/NullMaybe.ql

@@ -10,6 +10,7 @@
  *       correctness
  *       exceptions
  *       external/cwe/cwe-476
+ *       quality
  */
 
 import csharp