12175 rack with starting unit > 1 (#12778)

* 12175 add rack starting unit

* 12175 rack starting unit to svg

* verify devices can still fit if change rack starting_unit

* 12175 fix migration

* 12175 fix typo and test

* 12175 fix test

* 12175 fix max height calc display

* Misc cleanup & fixes

---------

Co-authored-by: Jeremy Stretch <jstretch@netboxlabs.com>

netbox/dcim/migrations/0174_rack_starting_unit.py

@@ -0,0 +1,17 @@
+# Generated by Django 4.1.9 on 2023-05-31 15:47
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('dcim', '0174_device_latitude_device_longitude'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='rack',
+            name='starting_unit',
+            field=models.PositiveSmallIntegerField(default=1),
+        ),
+    ]