[WIP]: Internalize vis editor URL state and implement rough UI-based undo/redo.

[cjcenizal]

Addresses

• Visualization and dashboard state, URLs, and sharing #7899
• Smaller state representation to fix IE errors due URL length #3947

Changes

• When a visualization is loaded via deep-link, state.js removes the vis state from the URL and stores it internally.
• share_object_url directive surfaces shareable URL (but has bugs).
• Undo/redo works via buttons in editor sidebar (needs styles).
• Unaddressed major edge case: using the history back button to navigate back to a visualization results in a default, empty visualization.

To-do

• Fix major edge case of back button not loading previous vis state.
• Fix complementary edge case of hitting back button after editing a vis, and then hitting the forward button to see your work in progress.
• Fix edge case of opening a different app and then re-opening Visualizations and seeing your work in progress.
• Generalize undo/redo mechanism.
• Generalize solutions to Dashboard and other places where URL state is long.
• Make sure undo/redo in sidebar isn't available in apps where it isn't used (e.g. Discover).
• Surface error if the URL can't be decoded (with suggestion to click a link instead of copy/pasting it directly for IE users).

Test cases

• Test that this works with IE and a Ridiculously Long URL (RLURL).
• Test this works when viewed via an IFRAME with the src set to a RLURL.
• Test that this works with the browser's history and results in a pleasant UX.
• Test that the links to visualizations that are generated throughout the app still work.

[tylersmalley]

This is closed in favor of #8022