Fix reporting of event path errors in MTRBaseDevice. (#26822)

Two main fixes here:

* Don't lose the prceise error if we have one in OnEventData.
* Use the right path key in our report dictionary for event errors.

The path key problem has not been shipped in any releases before, so no
backports needed.

The other changes are just aligning the attribute and event cases on checking
"is this a path we expected a report for?" before actually looking at the report
we got.

src/darwin/Framework/CHIP/MTRBaseDevice.mm

@@ -819,12 +819,14 @@ void OnAttributeData(
         //
         VerifyOrDie(!aPath.IsListItemOperation());
 
-        VerifyOrExit(aStatus.IsSuccess(), err = aStatus.ToChipError());
         VerifyOrExit(
             std::find_if(mAttributePathParamsList, mAttributePathParamsList + mAttributePathParamsSize,
                 [aPath](app::AttributePathParams & pathParam) -> bool { return pathParam.IsAttributePathSupersetOf(aPath); })
                 != mAttributePathParamsList + mAttributePathParamsSize,
             err = CHIP_ERROR_SCHEMA_MISMATCH);
+
+        VerifyOrExit(aStatus.IsSuccess(), err = aStatus.ToChipError());
+
         VerifyOrExit(apData != nullptr, err = CHIP_ERROR_INVALID_ARGUMENT);
 
         SuccessOrExit(err = app::DataModel::Decode(*apData, value));
@@ -852,6 +854,9 @@ void OnEventData(const EventHeader & aEventHeader, TLV::TLVReader * apData, cons
                          })
                 != mEventPathParamsList + mEventPathParamsSize,
             err = CHIP_ERROR_SCHEMA_MISMATCH);
+
+        VerifyOrExit(apStatus == nullptr, err = apStatus->ToChipError());
+
         VerifyOrExit(apData != nullptr, err = CHIP_ERROR_INVALID_ARGUMENT);
 
         SuccessOrExit(err = app::DataModel::Decode(*apData, value));
@@ -1366,7 +1371,7 @@ - (void)subscribeToAttributePaths:(NSArray<MTRAttributeRequestPath *> * _Nullabl
                            ConcreteEventPath pathCopy(*eventPath);
                            dispatch_async(queue, ^{
                                reportHandler(@[ @ {
-                                   MTRAttributePathKey : [[MTREventPath alloc] initWithPath:pathCopy],
+                                   MTREventPathKey : [[MTREventPath alloc] initWithPath:pathCopy],
                                    MTRErrorKey : [MTRError errorForCHIPErrorCode:error]
                                } ],
                                    nil);