Refactor: Rename SPA to Dashboard (#336)

packages/shutdown/order.go

pluginmgr/ui/plugins.go

plugins/dashboard/dashboard-packr.go

plugins/dashboard/drng_livefeed.go

plugins/dashboard/explorer_routes.go

plugins/dashboard/frontend/.gitignore

plugins/dashboard/frontend/.prettierrc

plugins/dashboard/frontend/README.md

plugins/dashboard/frontend/package.json

plugins/dashboard/frontend/src/app/App.tsx

plugins/dashboard/frontend/src/app/components/Dashboard.tsx

plugins/dashboard/frontend/src/app/components/Drng.tsx

...ns/dashboard/frontend/src/app/components/DrngLiveFeed.tsx

plugins/dashboard/frontend/src/app/components/Explorer.tsx

...ins/dashboard/frontend/src/app/components/Explorer404.tsx

...ard/frontend/src/app/components/ExplorerAddressResult.tsx

...ashboard/frontend/src/app/components/ExplorerLiveFeed.tsx

...rontend/src/app/components/ExplorerMessageQueryResult.tsx

...shboard/frontend/src/app/components/ExplorerSearchbar.tsx

plugins/dashboard/frontend/src/app/components/MPSChart.tsx