* [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
