Collapse PRs that are part of a stack into a single entry in the Pull requests tab

[relsunkaev]

Currently, I have a stack that's 22 diffs long and the 21 extra PR's currently pollute the pull requests tab. This makes it kinda difficult to find the "base pull request" and my team-members struggle to find their PRs amid the deluge of constantly updating entries. For me the "stack" is the base unit I want to be searching for instead of individual diffs within the stack.

[visory-kunal]

+1