fix: correcting submission button bug for MRF

[kathleenkhy]

Problem

Previous PR (#7186) to prevent the Submission button from showing for MRF Respondent #2 onwards resulted in a bug (and incident) where users would not be able to access the Admin view of non-payment forms' Thank You page.

The PR was subsequently reverted to undo the problem introduced. (#7231)

Solution

To add the use of Public Form Context to the parent of EndPageBlock (i.e. FormEndPage). The EndPageBlock component is also used in the Admin View (to show as a preview while the Admin use edits the form), resulting in an error because the component that is public-form is also rendered in admin-form.

Breaking Changes

• No - this PR is backwards compatible

Tests

• Create a non-payment form
• Proceed to the Thank You page tab

MRF Form test

• Create an MRF form
• Create 2 workflows
• Submit the 1st workflow - the Submit another response button should be present
• Submit the 2nd workflow - the Submit another response button should not be present

[KenLSM]

We should also refactor frontend/src/features/public-form/components/FormEndPage/components/EndPageBlock.tsx out of public-form and place it in a generic component folder, rather than one that implies it’s solely used for public-form i.e., possessing PublicFormContext.

It’s not very idiomatic and I can see myself getting conned by this gotcha.

[KenLSM]

LGTM!