Frontend for Flag Dependencies (CRs not enabled)

[khvn26]

Implement the following mockups (subject to change according to the comments below):

Comments:

• “Must be” column will be omitted for V1, and we’re assuming “must be enabled” for every dependency (see override details in 2.3.1 POST .../dependencies/{prerequisite_feature}.
• Clicking through a dependent feature navigates to the Dependencies tab of that feature.

[matthewelwell]

Dependencies coming from user-created segments should be marked as such, and clicking through those will redirect to a segment edit screen for that segment. (a dedicated "Edit Segment" button?)

We have agreed to descope the ability to create flag dependencies manually through segments for the first version. The reasoning being that this functionality is designed to be easy to use for less technical users. As such, we want to completely hide the fact that it is underpinned by segments at all in the first version.