[infra-if] add missing otInstance parameter to otPlatInfraIf APIs (#12662)

This commit updates the following `otPlatInfraIf` platform APIs to
include an `otInstance *` as their first parameter:

- `otPlatInfraIfHasAddress()`
- `otPlatInfraIfSendIcmp6Nd()`
- `otPlatInfraIfDiscoverNat64Prefix()`

Other APIs under `otPlatInfraIf` already follow this pattern. Passing
the `otInstance` pointer is the required standard for all platform
and public APIs; however, it was missed during the initial design of
these specific APIs.

While missing this parameter is often not a blocker on platforms using
a single OpenThread instance, it has become a blocker for simulations,
especially when multiple Border Routers are emulated in the same
simulation setup.

This change introduces a compatibility break for existing platform
implementations, however, it is necessary to support new use cases
(simulation of BRs). It also helps ensure consistent API design
across the stack.

tests/unit/test_routing_manager.cpp

@@ -287,14 +287,16 @@ uint32_t otPlatAlarmMilliGetNow(void) { return sNow; }
 //---------------------------------------------------------------------------------------------------------------------
 // otPlatInfraIf
 
-bool otPlatInfraIfHasAddress(uint32_t aInfraIfIndex, const otIp6Address *aAddress)
+bool otPlatInfraIfHasAddress(otInstance *aInstance, uint32_t aInfraIfIndex, const otIp6Address *aAddress)
 {
+    VerifyOrQuit(aInstance == sInstance);
     VerifyOrQuit(aInfraIfIndex == kInfraIfIndex);
 
     return AsCoreType(aAddress) == sInfraIfAddress;
 }
 
-otError otPlatInfraIfSendIcmp6Nd(uint32_t            aInfraIfIndex,
+otError otPlatInfraIfSendIcmp6Nd(otInstance         *aInstance,
+                                 uint32_t            aInfraIfIndex,
                                  const otIp6Address *aDestAddress,
                                  const uint8_t      *aBuffer,
                                  uint16_t            aBufferLength)
@@ -305,6 +307,7 @@ otError otPlatInfraIfSendIcmp6Nd(uint32_t            aInfraIfIndex,
     Log("otPlatInfraIfSendIcmp6Nd(aDestAddr: %s, aBufferLength:%u)", AsCoreType(aDestAddress).ToString().AsCString(),
         aBufferLength);
 
+    VerifyOrQuit(aInstance == sInstance);
     VerifyOrQuit(aInfraIfIndex == kInfraIfIndex);
 
     packet.Init(aBuffer, aBufferLength);