[SearchBar] Export common `search_bar/query` types

[PhaedrusTheGreek]

It is possible to supply a custom options.fieldValuesToQuery to Query.toESQuery, however much of the types required to work with that function are not exported from @elastic/eui:

Specifically,

import {
  AST,
  OperatorType,
  Value,
} from '@elastic/eui/src/components/search_bar/query/ast';
import { QueryContainer } from '@elastic/eui/src/components/search_bar/query/ast_to_es_query_dsl';
import { printIso8601 } from '@elastic/eui/src/components/search_bar/query/date_format';
import {
  dateValue,
  DateValue,
  isDateValue,
} from '@elastic/eui/src/components/search_bar/query/date_value';
import { isDateLike } from '@elastic/eui/src/services/predicate';