[mle] implement alternate RLOC16 usage during role transition (#10006)

This commit introduces a mechanism for a device transitioning from
child to router role to keep receiving frames addressed to its
previous short address for a brief period.

A new radio platform API, `otPlatRadioSetAlternateShortAddress()`, is
introduced. This allows the OT stack to configure an alternate short
address. Radio platform support for this function is indicated by the
`OT_RADIO_CAPS_ALT_SHORT_ADDR` capability in `otPlatRadioGetCaps()`
The same function can be used with `OT_RADIO_INVALID_SHORT_ADDR`
(`0xfffe`) to clear a previously set alternate short address. Support
for the new API is implemented in RCP and `RadioSpinel`, ensuring
backward compatibility by dynamically checking supported radio
capabilities.

MLE code is updated to instruct the radio to use the old child RLOC16
as an alternate address upon role transition. The MLE layer will
automatically clear the alternate address after eight seconds, or if
other state/mode changes occur. This eight-second window ensures the
new router can transmit four MLE Advertisement messages.

examples/platforms/utils/mac_frame.cpp

@@ -41,6 +41,15 @@ bool otMacFrameDoesAddrMatch(const otRadioFrame *aFrame,
                              otPanId             aPanId,
                              otShortAddress      aShortAddress,
                              const otExtAddress *aExtAddress)
+{
+    return otMacFrameDoesAddrMatchAny(aFrame, aPanId, aShortAddress, Mac::kShortAddrInvalid, aExtAddress);
+}
+
+bool otMacFrameDoesAddrMatchAny(const otRadioFrame *aFrame,
+                                otPanId             aPanId,
+                                otShortAddress      aShortAddress,
+                                otShortAddress      aAltShortAddress,
+                                const otExtAddress *aExtAddress)
 {
     const Mac::Frame &frame = *static_cast<const Mac::Frame *>(aFrame);
     bool              rval  = true;
@@ -52,7 +61,9 @@ bool otMacFrameDoesAddrMatch(const otRadioFrame *aFrame,
     switch (dst.GetType())
     {
     case Mac::Address::kTypeShort:
-        VerifyOrExit(dst.GetShort() == Mac::kShortAddrBroadcast || dst.GetShort() == aShortAddress, rval = false);
+        VerifyOrExit(dst.GetShort() == Mac::kShortAddrBroadcast || dst.GetShort() == aShortAddress ||
+                         (aAltShortAddress != Mac::kShortAddrInvalid && dst.GetShort() == aAltShortAddress),
+                     rval = false);
         break;
 
     case Mac::Address::kTypeExtended: