[WIP]Reconnection and Session improvements for Shell App

[samirmansour]

This is a new branch with the same functionality as terminal-decouple branch, but it is refactored to work with the new changes made to master. It is also an improvement on the reconnection experience for the user.

[johrstrom]

This PR didn't seem to redirect from /pun/dev/shell correctly. It seems that /pun/dev/shell redirects to /pun/dev/shell/ssh which returns a 404 with a header Content-Security-Policy | default-src 'none' so that the next request (for the favicon.ico) doesn't meet the content security policy.

Though c3c80d4 seems to fix it, it may cause other issues or need more work so I thought I'd still document the behaviour.

I've narrowed it down to trailing slashes. /pun/dev/shell/ works where /pun/dev/shell
doesn't. To replicate you'd simply need to manually edit the URL in the browser after resetting back to c5d3d95 and rebuilding.

Here's a screenshot.

[ericfranz]

The favicon issue is a preexisting issue. The url is wrong. It is to /favicon.ico not /public/favicon.ico.

[msquee]

@samirmansour There's a bug that causes an error to be thrown every other page refresh.

Here's the error:

I tracked down where the error is being thrown: https://github.com/microsoft/node-pty/pull/285/files#diff-32a8618c58cb849e9b5535ba19ffacc5R369-R375

Here's a thread I found with people having the same issue: microsoft/node-pty#220 (comment)

Are you able to reproduce this?

[msquee]

@samirmansour We should use Close Code 1001 instead of 4000. https://tools.ietf.org/html/rfc6455#section-7.4.1

From section 7.4.1 in RFC6455:
1001 indicates that an endpoint is "going away", such as a server
going down or a browser having navigated away from a page.

[samirmansour]

@samirmansour We should use Close Code 1001 instead of 4000. https://tools.ietf.org/html/rfc6455#section-7.4.1

From section 7.4.1 in RFC6455:
1001 indicates that an endpoint is "going away", such as a server
going down or a browser having navigated away from a page.

Discussed on Slack. Using code 4000 to signify that a user is closing the browser or navigating away to another site. If default codes are used then code 1001 will be sent by default for disconnection via wifi or if a user navigates away. WIFI loss should not terminate the terminal session, but user navigating away should.

[johrstrom]

This has merge conflicts at this point. What's more though, I think, is that I'm looking for a much simpler just attempt to reconnect a few times.