Hide / error on Libraries v2 pages if !librariesV2Enabled

[pomegranited]

Accessing the Library Home page (e.g. https://app.tagging-preview.staging.do.opencraft.hosting/course-authoring/library/lib:OpenCraft:TL) should give an error if the "disable v2 libraries" waffle flag is set.

It's totally fine if this error happens after the initial page load - since having v2 libraries enabled is the default we don't want to block loading until the waffle flag is checked.

[pomegranited]

@jmakowski1123 @lizc577 @sdaitzman @marcotuts This is ready for AC testing on the sandbox

[ChrisChV]

@jmakowski1123 @lizc577 @sdaitzman @marcotuts Friendly reminder that this is ready for AC testing on the sandbox

[jmakowski1123]

I'm not sure how to test this, since V2 is enabled on the sandbox?

[pomegranited]

@jmakowski1123 You can disable V2 on the sandbox using Django Admin:

1. In Django Admin, enable the contentstore.new_studio_mfe.disable_new_libraries flag to disable Libraries V2.
2. Load a library's home page in the Authoring MFE.
3. Verify that the error message is shown instead of the library content.
4. In Django Admin, disable the contentstore.new_studio_mfe.disable_new_libraries flag to enable Libraries V2.
5. Refresh the library's home page
6. Verify that the error message is no longer shown.