Dont make checkbox required always

[sverhoeven]

Fixes #67

To test

1. 1st way repeat steps in #67
   1. Goto haddock3-download app at https://app.netlify.com/sites/wonderful-noether-53a9e8/deploys/62d930fd6466c80009103c7d
   2. Instead of using netlify hosted app you can also run locally from root of repo run yarn && yarn dev and goto http://localhost:3000
   3. Add mdref node to workflow
   4. Expand molecule subform
   5. Press + button, this will add an unchecked checklbox
   6. Submit form
   7. Switch to text mode of workflow to see mol_shape_1 = false, before this PR it would have an invalid form.
2. 2nd way with story book
   1. from root of repo run yarn storybook
   2. Goto http://localhost:6007
   3. In left sidebar expand Checkbox
   4. Select Unchecked Checkbox In Array Is Submiteable story
   5. Press Submit button, should not complain and in actions tab have a new entry with onSubmit[0].formData key have value [false, true]. The story presses the submit button when opening the story, so you will see 2 actions.
3. 3rd way with unit test
   1. Change to packages/form/ and run yarn test
   2. It should run packages/form/src/IvresseCheckBoxWidget.test.tsxand pass.

~This PR also adds vitest to form package and upgrades rjsf to latest version.~ Moved to #100

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[sverhoeven]

This implementation blocks you from having a checkbox that must be checked to submit form. For example to agree to terms like a license.

[sverhoeven]

Thanks for reviewing