Re-implement DeviceClassifier in vanilla JS

[akhenry]

The DeviceClassifier loads on startup and detects the user agent and device that is being used to render Open MCT. It then attaches some additional CSS classes to the DOM based on the platform that it is rendering on.

Right now this is implemented in Angular, and needs to be re-implemented in vanilla JS.

AgentService needs to be re-implemented as is implemented in AngularJS.

MCTDevice can be removed as it is not in use anymore.

[davetsay]

Thanks for picking this one up, @mariuszr . Great work! Modified the issue description to include changes to AgentService and MCTDevice

[jvigliotta]

@davetsay can we get testing instructions?

[davetsay]

TESTING INSTRUCTIONS:

• Navigate to Open MCT using various devices and see that site functions as intended. Some functionality may be limited on smaller resolution devices or devices using Safari as the browser.
• When testing mobile devices, ensure toggling between landscape and portait mode works as intended (if using emulator can inspect element to see portrait or landscape classes)
• When testing touch devices, ensure touch works

[davetsay]

verified