Bewest/bolus subtypes


## Experiment with bolus subtypes

As discussed here: https://github.com/tidepool-org/data-model/pull/12/files#r10009973


```
{
    "initialDelivery": 3.6,
    "extendedDelivery": 1.7,
    "value": 5.3,
    "recommended": ???,
    "deviceTime": "time1",
    "duration": 14400000,
    "extended": true,
    "type": "bolus",
    "id": "19bbfa82-7ee8-4f5c-a8c7-d3b9821aece3"
}
```

Will actually be.

```
{
  "value": 3.6,
  "deviceTime": "time1",
  "joinKey": "myJoinKey",
  "type": "bolus",
  “subType”: “dual/normal”
}
{
  "value": 1.7,
  "deviceTime": "time1",
  "duration": 14400000,
  "joinKey": "myJoinKey"
  "type": "bolus",
  “subType”: “dual/square”
}
```

The "myJoinKey" is actually some unique (per-user) key that tells us that we can combine the records together.  A proposal for how to generate it on medtronic data is to use:

```
myJoinKey = f(record_timestamp, carelink_raw_id) // for first bolus or wizard, or whatever works
```