Adjust padding for visible focus outline on bottom bar buttons

[marcellamaki]

Summary

This PR redistributes some of the the padding from the outer div of the BottomBar to an inner div so the focus ring is not cut off. It does not change the visual appearance of the spacing (it add up to the same amount for the component).

On the bar on the content renderer, it adds some padding, for the same purpose.

References

Fixes #9464
Fixes #9181

Selection of some pages with the changes applied

Page	Screen
Content Renderer (Exercise)
Manage Channel Content
Manage Lesson Resources
Create Quiz
Taking a quiz

Reviewer guidance

I think since I made the changes to the bottom bar itself, most of the issues should be resolved. I cross referenced on multiple pages where it is implemented (see screenshots). However, it is possible there are cases that follow a similar pattern but do not use the BottomBar component (such as in the content page, where I added the changes separately).

Testing checklist

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Critical and brittle code paths are covered by unit tests

PR process

• PR has the correct target branch and milestone
• PR has 'needs review' or 'work-in-progress' label
• If PR is ready for review, a reviewer has been added. (Don't use 'Assignees')
• If this is an important user-facing change, PR or related issue has a 'changelog' label
• If this includes an internal dependency change, a link to the diff is provided

Reviewer checklist

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[pcenov]

LGTM - tested and verified as fixed in https://buildkite.com/learningequality/kolibri-python-package/builds/5624

[radinamatic]

Manual QA by @pcenov passed, good to go! 💯