C#: Add some more testcases and update test expected output.

Author: michaelnebel

csharp/ql/test/library-tests/conversion/span/Span.cs

@@ -61,6 +61,17 @@ public void M()
         string s = "";
         ReadOnlySpan<char> charReadOnlySpan = s; // string -> ReadOnlySpan<char>
 
+        // Various ref type conversions
+        Derived[] derivedArray = [];
+        ReadOnlySpan<Base> baseReadOnlySpan;
+        baseReadOnlySpan = derivedArray; // Derived[] -> ReadOnlySpan<Base>
+
+        ReadOnlySpan<object> objectReadOnlySpan;
+        objectReadOnlySpan = stringArray; // string[] -> ReadOnlySpan<object>
+
+        byte[][] byteByteArray = [];
+        objectReadOnlySpan = byteByteArray; // byte[][] -> ReadOnlySpan<object>
+
         // No conversion possible except for identity.
         ReadOnlySpan<InvariantInterface<Base>> invariantInterfaceBaseReadOnlySpan;
         ReadOnlySpan<InvariantInterface<Derived>> invariantInterfaceDerivedReadOnlySpan;

csharp/ql/test/library-tests/conversion/span/span.expected

@@ -1,25 +1,47 @@
 | ContravariantInterface<Base>[] | ReadOnlySpan<ContravariantInterface<Base>> |
 | ContravariantInterface<Base>[] | ReadOnlySpan<ContravariantInterface<Derived>> |
+| ContravariantInterface<Base>[] | ReadOnlySpan<object> |
 | ContravariantInterface<Base>[] | Span<ContravariantInterface<Base>> |
 | CovariantInterface<Derived>[] | ReadOnlySpan<CovariantInterface<Base>> |
 | CovariantInterface<Derived>[] | ReadOnlySpan<CovariantInterface<Derived>> |
+| CovariantInterface<Derived>[] | ReadOnlySpan<object> |
 | CovariantInterface<Derived>[] | Span<CovariantInterface<Derived>> |
+| Derived[] | ReadOnlySpan<Base> |
+| Derived[] | ReadOnlySpan<object> |
 | InvariantInterface<Derived>[] | ReadOnlySpan<InvariantInterface<Derived>> |
+| InvariantInterface<Derived>[] | ReadOnlySpan<object> |
 | InvariantInterface<Derived>[] | Span<InvariantInterface<Derived>> |
 | MixedInterface<Derived,Base>[] | ReadOnlySpan<MixedInterface<Base, Derived>> |
 | MixedInterface<Derived,Base>[] | ReadOnlySpan<MixedInterface<Derived, Base>> |
+| MixedInterface<Derived,Base>[] | ReadOnlySpan<object> |
 | MixedInterface<Derived,Base>[] | Span<MixedInterface<Derived, Base>> |
+| ReadOnlySpan<Base> | ReadOnlySpan<object> |
 | ReadOnlySpan<ContravariantInterface<Base>> | ReadOnlySpan<ContravariantInterface<Derived>> |
+| ReadOnlySpan<ContravariantInterface<Base>> | ReadOnlySpan<object> |
+| ReadOnlySpan<ContravariantInterface<Derived>> | ReadOnlySpan<object> |
+| ReadOnlySpan<CovariantInterface<Base>> | ReadOnlySpan<object> |
 | ReadOnlySpan<CovariantInterface<Derived>> | ReadOnlySpan<CovariantInterface<Base>> |
+| ReadOnlySpan<CovariantInterface<Derived>> | ReadOnlySpan<object> |
+| ReadOnlySpan<InvariantInterface<Base>> | ReadOnlySpan<object> |
+| ReadOnlySpan<InvariantInterface<Derived>> | ReadOnlySpan<object> |
+| ReadOnlySpan<MixedInterface<Base, Derived>> | ReadOnlySpan<object> |
 | ReadOnlySpan<MixedInterface<Derived, Base>> | ReadOnlySpan<MixedInterface<Base, Derived>> |
+| ReadOnlySpan<MixedInterface<Derived, Base>> | ReadOnlySpan<object> |
+| ReadOnlySpan<string> | ReadOnlySpan<object> |
 | Span<ContravariantInterface<Base>> | ReadOnlySpan<ContravariantInterface<Base>> |
 | Span<ContravariantInterface<Base>> | ReadOnlySpan<ContravariantInterface<Derived>> |
+| Span<ContravariantInterface<Base>> | ReadOnlySpan<object> |
 | Span<CovariantInterface<Derived>> | ReadOnlySpan<CovariantInterface<Base>> |
 | Span<CovariantInterface<Derived>> | ReadOnlySpan<CovariantInterface<Derived>> |
+| Span<CovariantInterface<Derived>> | ReadOnlySpan<object> |
 | Span<InvariantInterface<Derived>> | ReadOnlySpan<InvariantInterface<Derived>> |
+| Span<InvariantInterface<Derived>> | ReadOnlySpan<object> |
 | Span<MixedInterface<Derived, Base>> | ReadOnlySpan<MixedInterface<Base, Derived>> |
 | Span<MixedInterface<Derived, Base>> | ReadOnlySpan<MixedInterface<Derived, Base>> |
+| Span<MixedInterface<Derived, Base>> | ReadOnlySpan<object> |
+| Span<string> | ReadOnlySpan<object> |
 | Span<string> | ReadOnlySpan<string> |
+| String[] | ReadOnlySpan<object> |
 | String[] | ReadOnlySpan<string> |
 | String[] | Span<string> |
 | string | ReadOnlySpan<char> |