Add Leave project action

Proposal

We have an action for leaving a group but don't have one for leaving a project. We should add a Leave project action

Implementation guide

1. Create a new app/assets/javascripts/vue_shared/components/projects_list/projects_list_item_leave_modal.vue component based on app/assets/javascripts/vue_shared/components/groups_list/group_list_item_leave_modal.vue
2. Call DELETE /projects/:id/members/:user_id
3. Render the modal in app/assets/javascripts/vue_shared/components/projects_list/project_list_item_actions.vue