live: add boot entries into /refresh payload

Add 'efi' key into the refresh payload. The value for that key
has the following structure:

'efi': {
  'entries': [
    {
      "order": 0,
      "name": "Boot0000",
      "active": false,
      "description": "grub"
    },
    {
      "order": 1,
      "name": "Boot0001",
      "active": true,
      "description": "UEFI: PXE IP4 Realtek PCIe GBE Family Controller"
    }
  ]
}

If the client is not a EFI system it won't add the 'efi' field.
If an entry is not in the boot order it won't have the 'order' field.

src/live/ogOperations.py

@@ -157,6 +157,33 @@ class OgLiveOperations:
                 'checksum': image_checksum})
         return cache_contents
 
+    def _get_boot_entry_data(self):
+        data = {}
+
+        if not is_uefi_supported():
+            return data
+
+        try:
+            efibootmgr_out = run_efibootmgr_json()
+        except Exception as e:
+            logging.warning(e)
+            return data
+
+        data['entries'] = []
+        for idx, entry_name in enumerate(efibootmgr_out['BootOrder']):
+            entry_name = 'Boot' + entry_name
+            for entry in efibootmgr_out['vars']:
+                if entry['name'] == entry_name:
+                    entry['order'] = idx
+                    data['entries'].append(entry)
+                    break
+
+        for entry in efibootmgr_out['vars']:
+            if not 'order' in entry:
+                data['entries'].append(entry)
+
+        return data
+
     def _compute_md5(self, path, bs=2**20):
         m = hashlib.md5()
         with open(path, 'rb') as f:
@@ -756,6 +783,10 @@ class OgLiveOperations:
 
         json_body['cache'] = self._get_cache_contents()
 
+        boot_entry_data = self._get_boot_entry_data()
+        if boot_entry_data:
+            json_body['efi'] = boot_entry_data
+
         generate_menu(json_body['partition_setup'])
         generate_cache_txt()
         self._restartBrowser(self._url)