[mle] add TxMessage::AppendLinkAndMleFrameCounterTlvs() (#10378)

This commit adds `AppendLinkAndMleFrameCounterTlvs()` to
`Mle::TxMessage` for appending both Link and MLE Frame Counter TLVs.
This mirrors the existing `RxMessage` method for reading these
counters.

src/core/thread/mle.cpp

@@ -1791,8 +1791,7 @@ Error Mle::SendChildIdRequest(void)
 
     VerifyOrExit((message = NewMleMessage(kCommandChildIdRequest)) != nullptr, error = kErrorNoBufs);
     SuccessOrExit(error = message->AppendResponseTlv(mParentCandidate.mRxChallenge));
-    SuccessOrExit(error = message->AppendLinkFrameCounterTlv());
-    SuccessOrExit(error = message->AppendMleFrameCounterTlv());
+    SuccessOrExit(error = message->AppendLinkAndMleFrameCounterTlvs());
     SuccessOrExit(error = message->AppendModeTlv(mDeviceMode));
     SuccessOrExit(error = message->AppendTimeoutTlv(mTimeout));
     SuccessOrExit(error = message->AppendVersionTlv());
@@ -4513,6 +4512,17 @@ Error Mle::TxMessage::AppendMleFrameCounterTlv(void)
     return Tlv::Append<MleFrameCounterTlv>(*this, Get<KeyManager>().GetMleFrameCounter());
 }
 
+Error Mle::TxMessage::AppendLinkAndMleFrameCounterTlvs(void)
+{
+    Error error;
+
+    SuccessOrExit(error = AppendLinkFrameCounterTlv());
+    error = AppendMleFrameCounterTlv();
+
+exit:
+    return error;
+}
+
 Error Mle::TxMessage::AppendAddress16Tlv(uint16_t aRloc16) { return Tlv::Append<Address16Tlv>(*this, aRloc16); }
 
 Error Mle::TxMessage::AppendLeaderDataTlv(void)

src/core/thread/mle.hpp

@@ -1011,6 +1011,7 @@ private:
         Error AppendResponseTlv(const RxChallenge &aResponse);
         Error AppendLinkFrameCounterTlv(void);
         Error AppendMleFrameCounterTlv(void);
+        Error AppendLinkAndMleFrameCounterTlvs(void);
         Error AppendAddress16Tlv(uint16_t aRloc16);
         Error AppendNetworkDataTlv(NetworkData::Type aType);
         Error AppendTlvRequestTlv(const uint8_t *aTlvs, uint8_t aTlvsLength);

src/core/thread/mle_router.cpp

@@ -786,8 +786,7 @@ Error MleRouter::SendLinkAccept(const RxInfo      &aRxInfo,
     SuccessOrExit(error = message->AppendVersionTlv());
     SuccessOrExit(error = message->AppendSourceAddressTlv());
     SuccessOrExit(error = message->AppendResponseTlv(aChallenge));
-    SuccessOrExit(error = message->AppendLinkFrameCounterTlv());
-    SuccessOrExit(error = message->AppendMleFrameCounterTlv());
+    SuccessOrExit(error = message->AppendLinkAndMleFrameCounterTlvs());
 
     linkMargin = Get<Mac::Mac>().ComputeLinkMargin(aRxInfo.mMessage.GetAverageRss());
     SuccessOrExit(error = message->AppendLinkMarginTlv(linkMargin));
@@ -1698,8 +1697,7 @@ void MleRouter::SendParentResponse(Child *aChild, const RxChallenge &aChallenge,
 
     SuccessOrExit(error = message->AppendSourceAddressTlv());
     SuccessOrExit(error = message->AppendLeaderDataTlv());
-    SuccessOrExit(error = message->AppendLinkFrameCounterTlv());
-    SuccessOrExit(error = message->AppendMleFrameCounterTlv());
+    SuccessOrExit(error = message->AppendLinkAndMleFrameCounterTlvs());
     SuccessOrExit(error = message->AppendResponseTlv(aChallenge));
 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
     if (aChild->IsTimeSyncEnabled())