* feat(webview): enable context menu
This enables the ability (at least on MacOS) to reload the webview.
* fix(webview): add handler for webview error
Adding this un-covered the following error when trying to load a the printer page using http and hostname:
```
OnError: error loading page about:blank wxWEBVIEW_NAV_ERR_OTHER The resource could not be loaded because the App Transport Security policy requires the use of a secure connection.
```
* fix(macos): disable App Transport Security policy
Disables the [App Transport Security](https://developer.apple.com/documentation/bundleresources/information_property_list/nsapptransportsecurity) policy that blocks loading http urls (via hostname...ip addresses were fine because ip addresses can't have certs, so they would be excluded from the ATS restriction).
Resolves#791
