[test] add posix verification for OT 1.2 (#6070)

This change:
1. Adds new github action to verify posix app for OT 1.2.
2. Only enable compile flag OT_SIMULATION_VIRTUAL_TIME_UART in
   script/test for ot-rcp build target.
3. Allow mix use of posix node and ot-cli-mtd node by changing python
   test script to accept node type as parameter.
4. Remove CSL test from expect as it is covered by thread-1-2-posix
   tests.

tests/scripts/thread-cert/simulator.py

@@ -144,7 +144,6 @@ class VirtualTime(BaseSimulator):
 
     BLOCK_TIMEOUT = 10
 
-    RADIO_ONLY = os.getenv('RADIO_DEVICE') is not None
     NCP_SIM = os.getenv('NODE_TYPE', 'sim') == 'ncp-sim'
 
     _message_factory = None
@@ -246,7 +245,7 @@ class VirtualTime(BaseSimulator):
         return (addr[0], addr[1] - self.BASE_PORT)
 
     def _core_addr_from(self, nodeid):
-        if self.RADIO_ONLY:
+        if self._nodes[nodeid].is_posix:
             return ('127.0.0.1', self.BASE_PORT + self.port + nodeid)
         else:
             return ('127.0.0.1', self.port + nodeid)