FE sources migration (#6411)

* rename search terms endpoint

* refactor sources/index.js to typescript and /query api (no search terms yet)

* parametarize TRow type in IndexBreakdownRenderer

* refactor and plug in search terms to sources/index.tsx

* migrate sources details views

* add implicit dimension-not-empty filters on FE

* fix google-keywords.test.tsx

* fix E2E tests

* fix sources_legacy_test.exs

* avoid classname duplication between SearchTerms and IndexBreakdown

* refactor getFilterInfo to DimensionCell level