ui: Move all omnibox related logic into omnibox.ts

[stevegolton]

Currently a lot of the omnibox business logic is contained in the UIMain component. The Omnibox component in omnibox.ts is a purely a presentational widget.

The issue is that omnibox.ts is where one would expect to find all the omnibox logic, both business and presentational.

This patch moves all the business logic into a new component called Omnibox, and the original Omnibox presenational widget has been renamed to OmniboxWidget. Both classes appear in the same file - omnibox.ts.

This is a pure architectural change and contains 0 functional changes.

[primiano]

awesome