[joiner] support a new EUI-64 at run time (openthread#11200)

The otJoinerStart enables a mechanism for Thread
commissioning. The traditional Thread commissioning process uses
factory assigned EUI-64 of the device to derive the Joiner ID and
identify/filter a joiner (through steering data bloom filter).

But otJoinerStart does not allows users to have a new EUI-64 set
at run time.

On joiner side, when a new EUI-64 value is provided, the
Joiner code uses this new value to derive the Joiner ID and
identify/filter a joiner (through steering data bloom filter).

On commissioner side, users can use this new EUI-64 value.

src/core/meshcop/joiner.cpp

@@ -156,6 +156,7 @@ Error Joiner::Start(const char      *aPskd,
     }
     else
     {
+        SetIdFromIeeeEui64();
         SteeringData::CalculateHashBitIndexes(mId, filterIndexes);
     }