Implement `allow_force_push` for protected branches in API
<!-- This template is a great use for issues that are feature::additions or technical tasks for larger issues.--> ### Proposal <!-- Use this section to explain the feature and how it will work. It can be helpful to add technical details, design proposals, and links to related epics or issues. --> Allow updating the `allow_force_push` attribute of protected branch with the API. Please note that was implemented in the UI but not API, see: * https://gitlab.com/gitlab-org/gitlab/-/merge_requests/55261#note_591106026 * https://gitlab.com/gitlab-org/gitlab/-/merge_requests/62893#note_591114177 <!-- Consider adding related issues and epics to this issue. You can also reference the Feature Proposal Template (https://gitlab.com/gitlab-org/gitlab/-/blob/master/.gitlab/issue_templates/Feature%20proposal%20-%20detailed.md) for additional details to consider adding to this issue. Additionally, as a data oriented organization, when your feature exits planning breakdown, consider adding the `What does success look like, and how can we measure that?` section. --> <!-- Label reminders Use the following resources to find the appropriate labels: - https://gitlab.com/gitlab-org/gitlab/-/labels - https://about.gitlab.com/handbook/product/categories/features/ -->
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