Add pxeboot mtcAlive alarm to fault management

This update introduces a new maintenance group alarm ; 200.003

This new alarm is minor and management affecting if asserted.
It is considered management affecting for the upgrades case because
the pxeboot network is needed to upgrade a node.

The alarm represents a communication/messaging failure between the
active controller mtcAgent process and the mtcClient that runs
on each node.

Test Plan:

PASS: Verify alarm attributes
PASS: - code of 200.003
PASS: - assertion cause text
PASS: - proposed repair action text
PASS: - suppression option
PASS: - does not inhibit other alarms
PASS: - affect of assertion on upgrade healthcheck
PASS: Verify ability to assert and clear
PASS: Verify fm logging for the above assertion and clear

Story: 2010940
Task: 49789
Change-Id: I507d30213674c5b1e24fcfebe15c6a87bad74358
Signed-off-by: Eric MacDonald <eric.macdonald@windriver.com>

fm-doc/fm_doc/events.yaml

@@ -566,6 +566,22 @@
     Degrade_Affecting_Severity: none
     Context: starlingx
 
+200.003:
+    Type: Alarm
+    Description: <hostname> pxeboot network communication failure.
+    Entity_Instance_ID: host=<hostname>
+    Severity: minor
+    Proposed_Repair_Action: Administratively Lock and Unlock host to recover. If problem persists, contact next level of support.
+    Maintenance_Action: none
+    Inhibit_Alarms: False
+    Alarm_Type: communication
+    Probable_Cause: unknown
+    Service_Affecting: False
+    Suppression: False
+    Management_Affecting_Severity: warning
+    Degrade_Affecting_Severity: none
+    Context: starlingx
+
 200.004:
     Type: Alarm
     Description: |-