Fix checkbox issues

[AlexVelezLl]

Summary

Description of the change(s) you made

Recently we removed VCheckbox from the studio codebase, so we updated the Checkbox wrapper component to use KCheckbox instead, but this has bring a number of inconsistencies that havent been resolved yet. (Probably after this PR there could be any other place with a wrong behaviour).

Manual verification steps performed

I have manually checked all instances of <Checkbox> in the codebase and saw them rendered in the browser one by one.

Screenshots

Before	After
Disabled and hidden labels on AssesmentPreview
Select all not working in clipboard, and not showing copy actions
Indeterminate state on parent not working in clipboard
Selected parent not working
Select all on channel administration not working
Select all on users administration not working
Correct answers in AnswerEditor not working
Wrong alignment in accesibility options
Select channels on import from channels not working
Missing filter options label on import from other channel
Select channels on collections not working
Multi select inputs as licenses, formats, language, etc.

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Reviewer guidance

How can a reviewer test these changes?

Check all checkboxes on studio and ensure they are working.

References

Closes #4525

Comments

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Contributor's Checklist

PR process:

• If this is an important user-facing change, PR or related issue the CHANGELOG label been added to this PR. Note: items with this label will be added to the CHANGELOG at a later time
• If this includes an internal dependency change, a link to the diff is provided
• The docs label has been added if this introduces a change that needs to be updated in the user docs?
• If any Python requirements have changed, the updated requirements.txt files also included in this PR
• Opportunities for using Google Analytics here are noted
• Migrations are safe for a large db

Studio-specifc:

• All user-facing strings are translated properly
• The notranslate class been added to elements that shouldn't be translated by Google Chrome's automatic translation feature (e.g. icons, user-generated text)
• All UI components are LTR and RTL compliant
• Views are organized into pages, components, and layouts directories as described in the docs
• Users' storage used is recalculated properly on any changes to main tree files
• If there new ways this uses user data that needs to be factored into our Privacy Policy, it has been noted.

Testing:

• Code is clean and well-commented
• 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
• Any new interactions have been added to the QA Sheet
• Critical and brittle code paths are covered by unit tests

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Reviewer's Checklist

This section is for reviewers to fill out.

• 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

[rtibbles]

Code changes broadly make sense - screenshots give some confidence of the fixes! I'll take a quick through manually tomorrow to confirm.

[akolson]

Manual QA checks out. Thanks @AlexVelezLl! cc @rtibbles