Add ConnectionCheck for Dash Cards

Summary:
Check if there is an internet connection available before displaying information cards

• Ping example.com to check connection availability
• Wait for active internet connection to connect to plasma geolocation datasource
• Do not display information cards in not connected as they are dependent on GeoLocation data

Reviewers: Plasma

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D11142