## Summary
Added the `meta` prop to the `FilePicker` component, also pass this down
to the `FileUpload` component so that files created via the picker can
have meta set.
Close https://github.com/elastic/kibana/issues/151375
## How to test
1. Start Kibana with examples `yarn start --run-examples`
2. Go to the "Developer examples" in the side-nav menu under analytics
3. Go to "Files example"
4. Upload a file via the "Select file" button, should present an empty
file picker if you have no files, otherwise use the little upload
component bottom left
5. Either select files or dismiss the modal
6. Inspect the uploaded file and see the `myCool: 'meta'` entry included
with other metadata
## Screenshot
A file uploaded via the `FilePicker` in the "Files example" plugin.
<img width="897" alt="Screenshot 2023-02-16 at 11 41 06"
src="https://user-images.githubusercontent.com/8155004/219342872-c39b5d81-7421-4187-bb1c-d6815d80a3dc.png">
### Checklist
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
Changes files components (`FileUpload`, `FilePicker`) so that
their API returns the whole `fileJSON` instead of just and `id` (and
`kind`)
This is needed, for example, in image emebeddable to also get an
blurHash after uploading or picking an image without fetching the whole
file again.
* implement copy updates
* move rename file and update empty state copy
* update title to respect multi select vs single select
* added test for single select behaviour
* implement single select behaviour
* introduce and use multiple prop, default true
* pass multiple flag to state
* pass multiple upload flag to UI
* added single select story
* update files example to still support multiple select
* uploadMultiple -> selectMultiple
* remove use of non-existent i18n
* update filepicker react component tests
