Improve Popover API

[amelako]

Addresses #723.

Purpose

Some improvements for the Popover API and accessibility.

Approach and changes

Remove ref from trigger component in the Popover
Move the isOpen state outside of component
Add aria-expanded prop to trigger component
Add modifiers prop for custom Popper modifier support

Definition of done

• Development completed
• Reviewers assigned
• Unit and integration tests
• Meets minimum browser support
• Meets accessibility requirements

[sumup-clark]

Hey @amelako,
we are super excited that you are contributing! 🎉There's one more thing you need to do. Please accept our Contributor License Agreement. It helps you and us to collaborate on clear terms and focus on what we love most: code.

Thanks!

[changeset-bot]

🦋 Changeset detected

Latest commit: a3964db

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sumup/circuit-ui	Patch

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🔍 Inspect: https://vercel.com/sumup/oss-circuit-ui/HW82PbFKt2BXXWFi6nbstiKZUVP9
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[codecov]

Codecov Report

Merging #1013 (a3964db) into next (e76f2d0) will decrease coverage by 0.02%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##             next    #1013      +/-   ##
==========================================
- Coverage   91.05%   91.03%   -0.03%     
==========================================
  Files         161      161              
  Lines        2684     2689       +5     
  Branches      794      798       +4     
==========================================
+ Hits         2444     2448       +4     
- Misses        214      215       +1     
  Partials       26       26              

Impacted Files	Coverage Δ
packages/circuit-ui/components/Popover/Popover.tsx	96.87% <94.73%> (-1.44%)	⬇️

[connor-baer]

I like how the tests are simpler now ✨

Let's address two more things in this PR:

• Adding transitions for the bottom sheet on mobile
• Adding support for custom Popper modifiers