Add preAttack tactic to swagger (#10332)

Author: Amitbergman

specification/securityinsights/resource-manager/Microsoft.SecurityInsights/preview/2019-01-01-preview/SecurityInsights.json

@@ -3968,7 +3968,8 @@
         "Collection",
         "Exfiltration",
         "CommandAndControl",
-        "Impact"
+        "Impact",
+        "PreAttack"
       ],
       "type": "string",
       "x-ms-enum": {