Rename dateAdd to datetimeAdd (#26147)

docs/questions/query-builder/expressions-list.md

frontend/src/metabase-lib/expressions/config.js

frontend/src/metabase-lib/expressions/helper-text-strings.ts

.../metabase/scenarios/custom-column/cc-data-type.cy.spec.js

...ivers/mongo/src/metabase/driver/mongo/query_processor.clj

...mongo/test/metabase/driver/mongo/query_processor_test.clj

shared/src/metabase/mbql/normalize.cljc

shared/src/metabase/mbql/schema.cljc

shared/test/metabase/mbql/normalize_test.cljc

src/metabase/driver/sql/query_processor.clj

...se/query_processor_test/date_time_zone_functions_test.clj