Image upload error fix

[0nko]

Fixes #10329. The PR adds a notice when a site is in Private mode that the images are not accessible. Users were reporting that they can't upload images but it's not due to a bug in the app.

Light	Dark

To test:

1. Log in to a site that is Public
2. Go to Products -> Tap on some product
3. Verify the images are available (either existing images or button to add one)
4. In wp-admin set the site to Private mode in the Settings
5. In the app, switch to a different site and switch back (or re-login)
6. Go to Products -> Tap on some product
7. Verify a notice is displayed instead of an image gallery
8. Tap on the notice
9. Verify a privacy settings website is opened
10. Go back
11. In wp-admin set the site to Coming soon mode in the Settings
12. In the app, switch to a different site and switch back (or re-login)
13. Go to Products -> Tap on some product
14. Verify the images are available (either existing images or button to add one)

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 18.4. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

Generated by 🚫 Danger

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce Android
	Flavor	Jalapeno
	Build Type	Debug
	Commit	2c62580
	Direct Download	woocommerce-prototype-build-pr11383-2c62580.apk

[atorresveiga]

Outstanding work @0nko!!! Thanks for taking care of this. The code is working as expected and the UI is looking great.

np: I noticed that unit tests are failing, so we will need to update that file. Do you think it is worth adding a unit test covering the private site case to help document this case for future maintainers?

Pre-aproving this but we need to fix unit tests before merging the code

LGTM!

[0nko]

Thanks @atorresveiga! I added the tests.