Combine snippet embed and clone buttons into single code dropdown

...assets/javascripts/snippets/components/embed_dropdown.vue

app/assets/javascripts/snippets/components/show.vue

...pts/vue_shared/components/code_dropdown/code_dropdown.vue

...ue_shared/components/code_dropdown/code_dropdown_item.vue

...shared/components/code_dropdown/snippet_code_dropdown.vue

.../components/code_dropdown/snippet_code_dropdownstories.js

locale/gitlab.pot

qa/qa/page/component/snippet.rb

...eatures/browser_ui/3_create/snippet/share_snippet_spec.rb

spec/features/snippets/public_snippets_spec.rb

spec/frontend/snippets/components/embed_dropdown_spec.js

spec/frontend/snippets/components/show_spec.js

...e_shared/components/clone_dropdown/clone_dropdown_spec.js

...hared/components/code_dropdown/code_dropdown_item_spec.js

...vue_shared/components/code_dropdown/code_dropdown_spec.js

...ed/components/code_dropdown/snippet_code_dropdown_spec.js