WIP: Resolve "Display performance deltas between app deployments on Merge Request workflow"

This MR is a copy of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10981 to facilitate initial review.

Do not merge.

@godfat Could you take a look at this MR for initial review? Its based on mr-widget-redesign-review branch but it will be merged to master after mr-widget-redesign-review is merged.

assigned to @godfat

marked as a Work In Progress

@pchojnacki I marked this MR as WIP so that we would never merge this accidentally. I didn't check the tests very carefully as it seems still in progress? Others were all minor comments. Looks much better than before, thanks!

assigned to @pchojnacki

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• 4ba54c71 - remove unused metho, and cleanup some code. Add more queries to deployment queries.

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• b5f43cf7 - Remove unused method. Add more queries to deployment queries.

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Thanks for looking into it. I'm happy you liked it, I did write a few iterations before to hash out what works best because on top of this change new EE only features will also be implemented.

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• 3cff9460 - Remove unused method. Add more queries to deployment queries.

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@pchojnacki No problems. Thank you for making it easier to maintain. Let me know if you need more feedback.

resolved all discussions

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• a50804f4 - Wrap BaseQuery in module hierarchy

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• bc3b619e - Custom queries for prometheus

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