Keyboard event listeners for replay playback (aka: shortcuts)

[ryan953]

Depending on the replay duration, skipping through the session can be a finicky experience.
Power users, and would prefer to use keyboard short

The problem is that people familiar with Youtube and other video playing sites (basically everyone) expect to be able to play/pause the replay using their keyboard. Typically with the spacebar.

Power users would also benefit from other shortcuts that make it easier to scrub through the replay, and across the page.

We should come up with a set of keyboard shortcuts that the page will support and make them available at all times, whether the user is in full screen mode or not.

Some keys to start with:

• Spacebar to toggle play/pause on the replayContext
• left & right arrow keys to skip forward/backward 10s
• shift+left & shift+right to jump forwards and backwards to the next chapter/breadcrumb

maybe some more

We will need to make sure that keys don't conflict with each other. And that if someone is typing into a text box (to filter Console for example) shortcuts are not triggered.

[ryan953]

We should also talk about what happens if the replay is playable on the Issue Details page
and also how we teach people what the shortcuts are... is there a popup somewhere that has a list? idk!