Side Panel API: query position: left/right, close(), and focus(): tab to and from side panel

[solomonkinard]

High level ideas for discussion:

1. query position: left/right
2. close()
3. focus(): tab to and fro side panel

[dotproto]

From today's meeting, these items are under consideration by Chrome as work items for Summer of Code.

Given that someone may be working on focus() sooner than later, I'm going to prioritize the next revision of PR 817.

[carlosjeurissen]

Sidebar close() method
Issue: #521
PR: #837

Sidebar focus() method
Issue: #693
PR: #817

Sidebar query position
Issue: missing, could be this issue
PR: #838

[hharshas]

Chrome 140 now supports sidePanel.getLayout #CL.
The documentation of the new method is at https://developer.chrome.com/docs/extensions/reference/api/sidePanel#method-getLayout.