CLDR-15649 Dashboard using filters

-Add checkbox next to each notification category in Dashboard header

-The category is hidden if the checkbox is unchecked

-Error and Missing notifications still cannot be hidden with pre-existing right-side path-specific checkboxes, but they can be hidden categorically using the new checkboxes

-Show each path with notifications only once in Dashboard

-If a path has more than one notification, combine them on one line

-Perform data conversion on the front end; http response still has multiple notifications per path

-Refactor to avoid http code in Vue; call cldrAjax.mjs from cldrDash.mjs not from DashboardWidget.vue

-New classes DashData and DashEntry in cldrDash.mjs

-Use new method dashData.addEntriesFromJson for both whole-page json and single-path json

-Make hover titles clearer for circled abbreviations like EC for English Changed

-As before, always hide Abstained notifications if user is TC, but implement on the back end instead of the front end (simpler and more efficient)

-Turn off debug-logging in cldrTable (CLDR_TABLE_DEBUG) and cldrVote (CLDR_VOTE_DEBUG)