Add ability to upgrade agent binary from the UI:

• Add Upgrade agent binary action item to agent actions context menu that appears in table row, and on agent detail page. This opens confirm upgrade modal. This should only be visible when there is an upgrade available for that agent
• Add confirm upgrade modal
• Send necessary information in agent config down to agent for it to process upgrade (? I'm not sure what is needed here; some investigation should be done)
• Add Upgrade available next to agent version in agent Details tab that links to the same modal This should only be visible when there is an upgrade available for that agent