* Replace notify.warning with toastNotifications in region map, vega, index_pattern, redirect_when_missing, graph, monitoring, and ML
* Link to index patterns from Graph toast.
* Delete RouteBasedNotifier.
* Remove courierNotifier and SearchTimeout and ShardFailure errors.
* Remove warning and custom notifier types.
**Interface changes**
There are two goals behind the interface changes:
* Make it clearer which courier modules are meant for public consumption by exporting them from the top level.
* Simplify the courier object by removing responsibilities and focusing its responsibility solely on scheduling search requests via the fetch method and timefilter.refreshInterval Angular event.
I did this by taking the following steps:
* Removing redirectWhenMissing, indexPatterns, SearchSource, and SavedObject from the courier object. I also removed some unused methods from its interface.
* redirectWhenMissing is now a service registered on the kibana/url Angular module.
* indexPatterns is now a service registered on the kibana/index_patterns Angular module.
* SearchSourceProvider and SavedObjectProvider are now top-level exports of ui/courier.
* migrateFilter, decorateQuery, buildQueryFromFilters, and luceneStringToDsl are now top-level exports of ui/courier.
**Internal changes**
I also made some internal changes in an effort to organize the code clearly and reduce unnecessary complexity.
* I refactored the async code in CallClient to appear sync with async/await and encapsulated chunks of logic in helper functions. I also used an isAborted flag instead of overwriting the esPromise var with an enum.
* I combined Looper and SearchLooper into a single class and deleted unused functions.
* I reorganized the courier/fetch/request code into SearchRequest, SegmentedSearchRequest, and serializeFetchParams modules.
* Renamed various other methods and variables to improve clarity.
* [uiExports] migrate uiApp "uses" to explicit imports in apps
* [uiApp] update tests for getModules() method
* [optimize/uiExports] improve naming and comments
* [uiExports] sort imports so they load in the same order as before
* [testHarness] load hacks when testing in the browser
* [x-pack/uiExports] use new uiExports modules
* [testHarness] describe why we import uiExports/hacks
* [optimize] remove needless [].concat()
* [optimize/createUiExportsModule] string.includes > string.indexOf
* [uiExports/createUiExportsModule] remove needless capture of module exports
(cherry picked from commit e1a2fcbd96)
