[mlr] send MLR.req for local multicast addresses (#5248)

This commit includes:

- Adding compile configurations necessary for MLR features
- Adding source/header files necessary for MLR features
- Send MLR.req for local MAs on ThreadNetif
  - At most one MLR.req is outstanding
  - Reregistration according to PBBR configuration
  - Renewing periods according to PBBR configuration
- BBRs receive MLR.req with minimal processing and send MLR.rsp
- Add a test to verify that MLR.req is sent for local MAs.

tests/scripts/thread-cert/simulator.py

@@ -135,7 +135,7 @@ class VirtualTime(BaseSimulator):
     BASE_PORT = 9000
     MAX_NODES = 34
     MAX_MESSAGE = 1024
-    END_OF_TIME = 0x7FFFFFFF
+    END_OF_TIME = float('inf')
     PORT_OFFSET = int(os.getenv('PORT_OFFSET', '0'))
 
     BLOCK_TIMEOUT = 10