Start PR Reviews from Inline Comments

[grokys]

This PR adds a "Start a review" button to the inline comment peek view. When clicked it will start a pending review, and from this point all inline comments will be added to the pending review until the review is submitted:

Depends on #1549
Part of #1491

[meaghanlewis]

This PR looks good to me 👍

I mainly followed scenarios that I outlined here

Just a couple things to note:

1. The error that I get when trying to request changes or leave a comment review when there are no comments is too long and seems out of place.

For other errors don't we usually have a banner at the top (like 👇 ) ?

cc @grokys @donokuda

2. The cancel button doesn't seem to do anything
   

[donokuda]

For other errors don't we usually have a banner at the top (like 👇 ) ?

Yup, that's correct. I think the banner up there makes the most sense to show the error.

[drguthals]

I agree with @meaghanlewis regarding the error message.

I'm also noticing on VS2017 the font color is too dark for the changes list:

I also noticed that if you have "" in your comments you get an error:

I took out the quotes and it worked fine.

The interesting thing is that I started the inline comment, clicked "Start Your Review" and it started it, because I was able to see the "Continue your review", but the comment didn't actually get submitted until I took out the quotes.

And I confirmed only one version of the inline comment was saved:

Is that a known issue?