Refactor `Wrapper#find` for `Wrapper#findComponent`

Part 3

Automatic conversion of Vue Test Util `Wrapper#find` for
`Wrapper#findComponent` when applied to a Vue component.

From the Vue Test Util page:
https://v1.test-utils.vuejs.org/api/wrapper/#find

```
Deprecation warning

Using find to search for a Component is deprecated and will be removed.
Use findComponent instead. The find method will continue to work for
finding elements using any valid selector.
```