Boards - Refactor events without eventHub

app/assets/javascripts/boards/components/board_app.vue

app/assets/javascripts/boards/components/board_card.vue

...assets/javascripts/boards/components/board_card_inner.vue

app/assets/javascripts/boards/components/board_column.vue

app/assets/javascripts/boards/components/board_content.vue

...s/javascripts/boards/components/board_filtered_search.vue

app/assets/javascripts/boards/components/board_list.vue

...ssets/javascripts/boards/components/board_list_header.vue

app/assets/javascripts/boards/components/board_new_issue.vue

app/assets/javascripts/boards/components/board_new_item.vue

app/assets/javascripts/boards/components/board_top_bar.vue

...scripts/boards/components/issue_board_filtered_search.vue

app/assets/javascripts/boards/constants.js

...p/assets/javascripts/boards/components/board_new_epic.vue

...ts/javascripts/boards/components/epic_filtered_search.vue

ee/app/assets/javascripts/boards/components/epic_lane.vue

.../assets/javascripts/boards/components/epics_swimlanes.vue

...assets/javascripts/boards/components/issues_lane_list.vue

.../frontend/boards/components/board_filtered_search_spec.js

ee/spec/frontend/boards/components/board_list_header_spec.js