Edit UI: mock FF instead of disabling them for testing

## What is the problem?
In Edit-Ui, every view has code like this:

```javascript
// do not proceed if FF is disabled
// bypass this when Jest is running as FF are not fetched
if (!this.isJestRunning && !GetFeatureFlag('conversion-ui-enabled')) {
window.alert('Conversion filings are not available at the moment. Please check again later.')
this.$root.$emit('go-to-dashboard', true)
return
}
```

## What is the impact?
Feature flags cannot be tested and this block of code is duplicated on every view page.

## Proposed solution
Use a Jest mock for GetFeatureFlag