Require Padatious intents to be trained before service ready.

Previously the Skill Service would report ready as soon as all
Skills were loaded. This means that some valid intents would could
not be triggered despite the system as a whole reporting that it
was ready.

mycroft/skills/__main__.py

@@ -19,6 +19,7 @@ directory.  The executable gets added to the bin directory when installed
 (see setup.py)
 """
 import time
+from dataclasses import dataclass
 
 from lingua_franca import load_languages
 
@@ -79,10 +80,15 @@ def main(alive_hook=on_alive, started_hook=on_started, ready_hook=on_ready,
     SkillApi.connect_bus(bus)
 
     # _wait_for_internet_connection()
+    padatious_training = _intent_training_status()
+
+    def handle_intents_trained(_):
+        padatious_training.complete = True
+    bus.once('mycroft.skills.trained', handle_intents_trained)
     skill_manager = SkillManager(bus, watchdog)
     skill_manager.load_on_startup()
 
-    while not skill_manager.is_all_loaded():
+    while not all((skill_manager.is_all_loaded(), padatious_training.complete)):
         time.sleep(0.1)
     _set_initialize_ended_status(bus, status)
     skill_manager.start()
@@ -122,6 +128,11 @@ def _register_intent_services(bus):
     return service
 
 
+@dataclass
+class _intent_training_status:
+    complete: bool = False
+
+
 def _wait_for_internet_connection():
     while not connected():
         time.sleep(1)