feat(device): Record inventory date and show as part of details

inventory date is added when an inventory is processed

!8 #2

app/itam/forms/device/device.py

@@ -1,6 +1,7 @@
 from django import forms
 from django.db.models import Q
 
+from app import settings
 from itam.models.device import Device
 
 
@@ -17,3 +18,14 @@ class DeviceForm(forms.ModelForm):
             'uuid',
             'device_type',
         ]
+
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self.fields['_lastinventory'] = forms.DateTimeField(
+            label="Last Inventory Date",
+            input_formats=settings.DATETIME_FORMAT,
+            initial=kwargs['instance'].inventorydate,
+            disabled=True
+        )