Add lint check for android.app.Fragment without v13 dependency

[hotchemi]

https://github.com/hotchemi/PermissionsDispatcher/pull/306#issuecomment-298237438

[mannodermaus]

Some additional context:

We allow our users to exclude the support for "Native Fragments" (i.e. android.app.Fragment) included in PermissionsDispatcher. To do this, the Gradle dependency needs to have an exclude clause that skips the transitive dependency on support-v13.

If a user accidentally removes this transitive dependency, but still tries to use PermissionsDispatcher with an android.app.Fragment, their app will crash. To prevent this behavior, this Lint check was proposed. It should:

• Find sub-classes of android.app.Fragment annotated with @RuntimePermissions
• Perform a Class.forName lookup of any class in the support-v13 library (preferably FragmentCompat) - this lookup should be performed only once, to keep reflection penalties low
• If it's able to detect the support-v13 class, everything is OK - if not, the issue is triggered

I'd say the severity of this Lint issue would be pretty high (at least an 8). In terms of the naming, how about something like MissingFragmentPermissionsDependency?

[hotchemi]

Happy closing 😇 ref: https://github.com/permissions-dispatcher/PermissionsDispatcher/issues/445