`Last 7 days` option for Cycle Analytics view

Motivation

Currently, Cycle Analytics cycles are 30 days or 90 days long.
A 30 days view is too long for my team, so I built a quick thing showing almost the same data but for a week only.
I felt this could be useful for other teams as well, doing weekly meetings/planning/sprints/wathever-you-name-it.

I can't say of courses how many of GitLab users are interested on weekly glimpses, but I guess a lot are doing shorter dev cycles (from idea to production) than a full month or 3 months.

Proposal

Links / references

MR making it real at !13443 (merged)

Documentation blurb

Overview

What is it? Why should someone use this feature? What is the underlying (business) problem? How do you use this feature?

Use cases

Who is this for? Provide one or more use cases.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.

• Feature assurance
• Documentation
• Added to features.yml