Bugzilla

**Steps to reproduce**
1. Open Netmonitor
2. Open Split console and evaluate

```js
fetch(`data:application/json,{"test":{"small": 12, "big": 1516340399466235648,"precise": 3.141592653589793238462643383279}}`)
```

3. Select the request in Netmonitor, and select the Response tab

**Expected results**

The parsed JSON values are the same as the response

**Actual results**

The values are truncated because we're using `JSON.parse` (same cause as in JSON Viewer)

---

What we're doing for the JSON Viewer in Bug 1431808 should be easy to apply to the Netmonitor as well

**Steps to reproduce**
1. Navigate to https://fx-devtools-netmonitor-json-lossy-number.glitch.me/
2. Open Netmonitor
3. Click on the "fetch JSON" button in the page
4. Select the request in Netmonitor, and select the Response tab (same issue can be seen in the Request tab as the fetch call has a JSON `body`)

**Expected results**

The parsed JSON values are the same as the response

**Actual results**

The values are truncated because we're using `JSON.parse` (same cause as in JSON Viewer)

---

What we're doing for the JSON Viewer in Bug 1431808 should be easy to apply to the Netmonitor as well