1316220 - [geckoview] Split o.m.g.annotations into GeckoView and Fennec parts

Status: NEW

(GeckoView :: General, defect, P3)

Description

[Nick Alexander :nalexander [he/him]]

The JNI bits should be in GeckoView, but @ReflectionTarget and @RobocopTarget should be Fennec-specific.

For @ReflectionTarget, I see a usage that is covered by Proguard (https://dxr.mozilla.org/mozilla-central/source/mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoView.java#151) and two that are specific to FxA/Push integration (https://dxr.mozilla.org/mozilla-central/source/mobile/android/geckoview/src/main/java/org/mozilla/gecko/EventDispatcher.java#164).  Getting rid of that reflection is really not easy, so I think it makes sense to keep the reflection (boo!) but have the reflection target be in Fennec (not GeckoView).  That is, move the logic of the helper function at https://dxr.mozilla.org/mozilla-central/source/mobile/android/services/src/main/java/org/mozilla/gecko/fxa/FxAccountDeviceRegistrator.java#272 into Fennec, make that helper @ReflectionTarget, and then reflect to it in the FxA code.  That'll let us move the ReflectionTarget stuff to Fennec, where it belongs.