* Expose core api types in /public and /server

* Export CoreStart from core/public

* Export Server and Public from 'kibana'

* Cast frozen object type back to original

The exported type `InjectedMetadataStart` derives it's type from the returned values.
Since it's internal state is frozen the type changes to `ReadOnly<`. However, consumers
of the API shouldn't have to know or care about this type.

* Be more selective with what gets exported

* Fix type imports in tests

* Fix type errors

* Remove src/type_exports.ts

* More remove src/type_exports.ts

* Remove build:types

* Fix bootstrap import

* Expose internal API's at the top level

Exposing the internal API's at the top level of core/public and core/server
makes it obvious that these API's are consumed outside these modules. Marking
these @internal ensures they don't get exported as part of the documentation.

* Fix tests

* Put core/{public/server} in their own namespaces