Increase severity for endpoint test NVV validation

This commit increases the validation event severity, from WARNING to DANGER,
for cases where the input to an operationInputs endpoint test does not match
the requirements of the input shape.

There does not appear to be a use case for this behavior and it is believed
that this was mistakenly lowered from ERROR to WARNING in a previous commit.
It is increased only to DANGER to allow for a suppression in cases we do not
foresee.

Author: kstich

smithy-rules-engine/src/main/java/software/amazon/smithy/rulesengine/traits/EndpointTestsTraitValidator.java

@@ -64,7 +64,7 @@ public List<ValidationEvent> validate(Model model) {
                         // so lower the severity before emitting.
                         if (testCase.getExpect().getError().isPresent()) {
                             for (ValidationEvent event : operationInputEvents) {
-                                events.add(event.toBuilder().severity(Severity.WARNING).build());
+                                events.add(event.toBuilder().severity(Severity.DANGER).build());
                             }
                         } else {
                             events.addAll(operationInputEvents);

smithy-rules-engine/src/test/resources/software/amazon/smithy/rulesengine/traits/errorfiles/missing-required-values.errors

@@ -1,2 +1,2 @@
 [WARNING] smithy.example#InvalidService: This shape applies a trait that is unstable: smithy.rules#endpointTests | UnstableTrait
-[WARNING] smithy.example#InvalidService: The operationInput value for an endpoint test does not match the operation's input shape: Missing required structure member `fizz` for `smithy.example#GetThingInput` | EndpointTestsTrait
+[DANGER] smithy.example#InvalidService: The operationInput value for an endpoint test does not match the operation's input shape: Missing required structure member `fizz` for `smithy.example#GetThingInput` | EndpointTestsTrait