Enable bulk resolve and restore buttons

...ets/javascripts/todos/components/mixins/bulk_mutations.js

.../components/mutations/bulk_resolve_todos.mutation.graphql

...s/components/mutations/bulk_snooze_todos.mutation.graphql

...components/mutations/bulk_unsnooze_todos.mutation.graphql

...mponents/mutations/undo_mark_all_as_done.mutation.graphql

...assets/javascripts/todos/components/snooze_todo_modal.vue

app/assets/javascripts/todos/components/todos_app.vue

app/assets/javascripts/todos/components/todos_bulk_bar.vue

app/assets/javascripts/todos/constants.js

config/feature_flags/beta/todos_bulk_actions.yml

locale/gitlab.pot

spec/frontend/todos/components/todos_app_spec.js

spec/frontend/todos/components/todos_bulk_bar_spec.js