Label dpi config (#3208)

* Updates for label printing settings:

- Make LABEL_ENABLE a global setting
- Add LABEL_DPI setting (default = 300)
- Add new global settings tab

* Use the configured DPI when printing labels

InvenTree/common/models.py

@@ -1008,6 +1008,23 @@ class InvenTreeSetting(BaseInvenTreeSetting):
             'validator': InvenTree.validators.validate_part_name_format
         },
 
+        'LABEL_ENABLE': {
+            'name': _('Enable label printing'),
+            'description': _('Enable label printing from the web interface'),
+            'default': True,
+            'validator': bool,
+        },
+
+        'LABEL_DPI': {
+            'name': _('Label Image DPI'),
+            'description': _('DPI resolution when generating image files to supply to label printing plugins'),
+            'default': 300,
+            'validator': [
+                int,
+                MinValueValidator(100),
+            ]
+        },
+
         'REPORT_ENABLE': {
             'name': _('Enable Reports'),
             'description': _('Enable generation of reports'),
@@ -1389,12 +1406,6 @@ class InvenTreeUserSetting(BaseInvenTreeSetting):
             'default': True,
             'validator': bool,
         },
-        'LABEL_ENABLE': {
-            'name': _('Enable label printing'),
-            'description': _('Enable label printing from the web interface'),
-            'default': True,
-            'validator': bool,
-        },
 
         "LABEL_INLINE": {
             'name': _('Inline label display'),