Refactor header components and add talons

[sirugh]

This PR is largely a refactor of header with some moving of code to talons.

• OnlineIndicator has been moved under the Header/ directory as it didn't make sense as a standalone component.
• I've added context to some components such as cartTrigger so that they can more easily be used independently of the Header at a later time.
• I removed cartCounter as it was a with minimal styling.
• I inlined icons rather than passing them as children of some of the triggers.

[sirugh]

Unused classes.

[sirugh]

Renamed props and included SearchIcon directly in the trigger component.

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[jimbo]

Nicely done all around. 👍