[EMSUSD-24] USD Camera viewport refresh issue

**Describe the bug**
While looking through a USD Camera it does not update when applying transforms to a parent prim

**Steps to reproduce**
Steps to reproduce the behavior:

`rootlayer.usda`
```
#usda 1.0
(
)

def Xform "group01"
{
double3 xformOp:translate = (0, 0, 0)
uniform token[] xformOpOrder = ["xformOp:translate"]

def Camera "Camera01"
{
}
}
```

1. Load rootlayer.usda
2. Apply transforms to the parent prim group01
3. The viewport which is looking through the USD camera does not update
4. Scrub the timeline or toggle "Camera01" visibility
5. The viewport will update

**Expected behavior**
We would expect the camera viewport to update immediately after transforms are applied to the parent prim

**Attachments**

**Specs (if applicable):**
- CentOS 7.8
- gcc-6.3
- maya-223
- Maya USD commit SHA
- Pixar USD commit SHA