fix(compiler): add failing test for spread of empty interface

`Intf` has no implementations. As written in the spec, doing a `... on
Intf` fragment spread should never work, as the set of possible types is
empty and can never intersect with the parent type. However,
implementations like graphql-js and graphql-go have an early check,
accepting the fragment if the type condition is equal to the parent
type. This tests reproduces that.

We may want to align with graphql-js and graphql-go rather than the spec
here for compatibility? Though it's not something that's likely to
happen in the real world.

Ref graphql/graphql-spec#1109

crates/apollo-compiler/test_data/ok/0116_interface_without_implementations.graphql

@@ -0,0 +1,16 @@
+type Query {
+  intf: Intf
+}
+interface Intf {
+  nothing: Int
+}
+
+query SelectDirectly {
+  intf { nothing }
+}
+
+query UsingInlineFragment {
+  intf {
+    ... on Intf { nothing }
+  }
+}

crates/apollo-compiler/test_data/serializer/ok/0116_interface_without_implementations.graphql

@@ -0,0 +1,21 @@
+type Query {
+  intf: Intf
+}
+
+interface Intf {
+  nothing: Int
+}
+
+query SelectDirectly {
+  intf {
+    nothing
+  }
+}
+
+query UsingInlineFragment {
+  intf {
+    ... on Intf {
+      nothing
+    }
+  }
+}