Fixes#20694
Implements super basic new platform `core` system, which includes two services: `core.injectedMetadata` and `core.legacyPlatform`. The `core` currently has two responsibilities:
1. read the metadata from the DOM and initialize the `ui/metadata` module with legacy metadata, proving out how we plan to expose data from the new platform through the existing APIs/modules to the legacy platform.
2. bootstrap the legacy platform by loading either `ui/chrome` or `ui/test_harness`
Because `core` mutates the `ui/metadata` module before bootstrapping the legacy platform all existing consumers of `ui/metadata` won't be impacted by the fact that metadata loading was moved into the new platform. We plan to do this for many other services that will need to exist in both the legacy and new platforms, like `ui/chrome` (see #20696).
* [eslint] unify resolver configs
Our eslint resolver settings currently rely on the fact that we define
our resolver with a string globally, and an object in the overrides.
This causes the override value to completely override/replace the global
setting, which is desired, but when the global setting is converted to
an object they are merged, causing both resolvers to run.
This is a problem because some dependencies in the UI side of things
will resolve with the node resolver, but will resolve incorrectly
because they are intended to use some webpack specific override.
While trying to add TypeScript I needed to pass argument to the node
resolver which uncovered this issue. The change here moves us away from
using the node resolver directly and instead uses the kibana resolver
with `forceNode: true` set when linting server code and `forceNode:
false` when resolving imports that will be handled by webpack.
* [import-resolver] use object spread operator
* [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)
