chore(sonarr): add 720p CF (#1896)

Creating a 720p custom format for Sonarr.

This is following the 2160p and 1080p formats already available for Sonarr, plus the 2160p, 1080p and 720p formats for Radarr, to complete the set.

Hash created via https://md5.gromweb.com/?string=Sonarr+720p

docs/json/sonarr/cf/720p.json

@@ -0,0 +1,19 @@
+{
+  "trash_id": "c99279ee27a154c2f20d1d505cc99e25",
+  "trash_scores": {
+    "default": 5
+  },
+  "name": "720p",
+  "includeCustomFormatWhenRenaming": false,
+  "specifications": [
+    {
+      "name": "720p",
+      "implementation": "ResolutionSpecification",
+      "negate": false,
+      "required": true,
+      "fields": {
+        "value": 720
+      }
+    }
+  ]
+}