Edit escalation policy

...n_policies/components/add_edit_escalation_policy_form.vue

..._policies/components/add_edit_escalation_policy_modal.vue

...ation_policies/components/escalation_policies_wrapper.vue

...ipts/escalation_policies/components/escalation_policy.vue

.../javascripts/escalation_policies/graphql/cache_updates.js

...aphql/mutations/update_escalation_policy.mutation.graphql

...ion_policies/__snapshots__/escalation_policy_spec.js.snap

...calation_policies/add_edit_escalation_policy_form_spec.js

...alation_policies/add_edit_escalation_policy_modal_spec.js

...ec/frontend/escalation_policies/escalation_policy_spec.js

...end/escalation_policies/escalation_policy_wrapper_spec.js

locale/gitlab.pot