Add support for getting gear attached to an activity

Uses the `gear-service` to get a list of JSON objects

Example data:

```json
[
    {
        "gearPk": 12345678,
        "uuid": "abcdef12345678abcdef12345678",
        "userProfilePk": 12345,
        "gearMakeName": "Other",
        "gearModelName": "Unknown Bike",
        "gearTypeName": "Bike",
        "gearStatusName": "active",
        "displayName": "gray",
        "customMakeModel": "Marin Headlands 1",
        "imageNameLarge": null,
        "imageNameMedium": null,
        "imageNameSmall": null,
        "dateBegin": "2022-02-18T00:00:00.0",
        "dateEnd": null,
        "maximumMeters": 643737.6000000001,
        "notified": true,
        "createDate": "2022-06-23T18:37:07.0",
        "updateDate": "2022-07-10T18:03:00.0"
    },
    {
        "gearPk": 12345679,
        "uuid": "bcdef12345678abcdef12345678a",
        "userProfilePk": 12345,
        "gearMakeName": "Other",
        "gearModelName": "Unknown Shoes",
        "gearTypeName": "Shoes",
        "gearStatusName": "active",
        "displayName": "bike",
        "customMakeModel": "Shimano RC3",
        "imageNameLarge": null,
        "imageNameMedium": null,
        "imageNameSmall": null,
        "dateBegin": "2022-05-17T00:00:00.0",
        "dateEnd": null,
        "maximumMeters": 643738.0,
        "notified": true,
        "createDate": "2022-06-23T18:39:00.0",
        "updateDate": "2022-07-10T18:03:00.0"
    }
]
```

garminexport/backup.py

@@ -8,12 +8,20 @@
 
 log = logging.getLogger(__name__)
 
-supported_export_formats = ["json_summary", "json_details", "gpx", "tcx", "fit"]
+supported_export_formats = [
+    "json_summary",
+    "json_details",
+    "gear",
+    "gpx",
+    "tcx",
+    "fit",
+]
 """The range of supported export formats for activities."""
 
 format_suffix = {
     "json_summary": "_summary.json",
     "json_details": "_details.json",
+    "gear": "_gear.json",
     "gpx": ".gpx",
     "tcx": ".tcx",
     "fit": ".fit"
@@ -132,6 +140,13 @@ def download(client, activity, retryer, backup_dir, export_formats=None):
         with codecs.open(dest, encoding="utf-8", mode="w") as f:
             f.write(json.dumps(activity_details, ensure_ascii=False, indent=4))
 
+    if 'gear' in export_formats:
+        log.debug('getting gear for %s', id)
+        activity_gear = retryer.call(client.get_activity_gear, id)
+        dest = os.path.join(backup_dir, export_filename(activity, 'gear'))
+        with codecs.open(dest, encoding='utf-8', mode='w') as f:
+            f.write(json.dumps(activity_gear, ensure_ascii=False, indent=4))
+
     not_found_path = os.path.join(backup_dir, not_found_file)
     with open(not_found_path, mode="a") as not_found:
         if 'gpx' in export_formats:

garminexport/garminclient.py

@@ -383,6 +383,29 @@ def get_activity_tcx(self, activity_id):
                 activity_id, response.status_code, response.text))
         return response.text
 
+    @require_session
+    def get_activity_gear(self, activity_id):
+        """Return a list of JSON objects describing the gear used in an activity,
+        if any. If there is no gear attached, the result will be an empty list.
+
+        :param activity_id: Activity identifier.
+        :type activity_id: int
+        :returns: The JSON object describing the gear or ``None`` if there is
+         no gear attached
+        :rtype list
+        """
+        response = self.session.get(
+            f'https://connect.garmin.com/proxy/gear-service/gear/filterGear?activityId={activity_id}',
+        )
+        if response.status_code == 400:
+            return None
+        if response.status_code != 200:
+            raise Exception(
+                f'failed to fetch gear for activity {activity_id}: {response.status_code}\n'
+                f'{response.text}'
+            )
+        return response.json()
+
     def get_original_activity(self, activity_id):
         """Return the original file that was uploaded for an activity.
         If the activity doesn't have any file source (for example,