Adds ability to destroy AI Agents

doc/api/graphql/reference/index.md

...sets/javascripts/ml/ai_agents/components/agent_delete.vue

...assets/javascripts/ml/ai_agents/components/agent_list.vue

ee/app/assets/javascripts/ml/ai_agents/constants.js

ee/app/assets/javascripts/ml/ai_agents/event_hub.js

...gents/graphql/mutations/destroy_ai_agent.mutation.graphql

ee/app/assets/javascripts/ml/ai_agents/views/edit_agent.vue

ee/app/assets/javascripts/ml/ai_agents/views/show_agent.vue

ee/app/graphql/ee/types/mutation_type.rb

ee/app/graphql/mutations/ai/agents/base.rb

ee/app/graphql/mutations/ai/agents/destroy.rb

ee/app/graphql/mutations/ai/agents/update.rb

ee/app/services/ai/agents/destroy_agent_service.rb

ee/spec/frontend/ml/ai_agents/graphql/mocks.js

ee/spec/frontend/ml/ai_agents/views/edit_agent_spec.js

ee/spec/requests/api/graphql/ai/agents/destroy_spec.rb

ee/spec/services/ai/agents/destroy_agent_service_spec.rb

locale/gitlab.pot