Add support for the BP Docs plugin / BuddyBoss docs features.

[ideadude]

Users of the BuddyBoss or the BuddyPress Docs plugin want to restrict who can view and/or upload docs.

https://wordpress.org/plugins/buddypress-docs/

We have this gist, which filters the URL of where the doc is stored and restricts docs from being downloaded: https://gist.github.com/ideadude/dde67a868aa527f8e2793c1cf80bf6b9#file-my_redirect_away_from_docs-php-L52

But users also want to be able to hide docs from profiles and feeds in general, want the preview (which seems to have gotten better) from showing what's in a doc to non-members, and block people from uploading docs.

Users also want it right in the settings instead of in a gist. So I imagine something to:

1. Detect that the BuddyBoss or the BP Docs is active.
2. If so, add 2 extra settings for restrictions. (a) Can members of this level view documents? (b) Can members of this level upload documents?
3. Find the filters we need to to restrict things.

Questions:

1. Is the BuddyBoss docs feature the same as the BP Docs one? (I feel like the settings are in different places or a little different, but they are similar underneath... for now.)
2. Should we support more granular restrictions? e.g. only allow members to upload docs to groups and/or view docs in groups they are members of. What's the most common use case? What cases were these features added for first? What can be altered via gist?

[kimwhite]

BuddyBoss Document upload is now included in the "Media Uploading" Component. This includes "Allow members to upload photos, documents, videos, emojis, and animated GIFs, and to organize photos and videos into albums and documents into folders."

Can we build in to activate this feature by level like other component options?