Include a special icon for overrides bindings

[JakeWharton]

When viewing the bindings corresponding to an injection, it's not obvious which ones are the production ones (which you usually want) and which ones are the test/dev ones (which you don't).

Dagger knows this via the overrides=true option on the declaring module. Production code usually doesn't set this; test code usually does.

We should either add an icon or split the list into two parts, with production stuff up top and "test" stuff below.

cc @swankjesse