Consolidate baseContext, BaseContext, and BaseModuleContext

blueprint.BaseModuleContext is the set of methods available to all
module-specific calls (GenerateBuildActions or mutators).  The
android package split the same functionality across baseContext (nee
androidBaseContext), BaseModuleContext, and BaseContext.
Consolidate all of them into android.BaseModuleContext.

Test: m checkbuild
Change-Id: I2d7f5c56fd4424032cb93edff6dc730ff33e4f1e
diff --git a/apex/apex.go b/apex/apex.go
index aed7d6f..41a21c9 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -552,7 +552,7 @@
 	}
 }
 
-func (a *apexBundle) getCertString(ctx android.BaseContext) string {
+func (a *apexBundle) getCertString(ctx android.BaseModuleContext) string {
 	certificate, overridden := ctx.DeviceConfig().OverrideCertificateFor(ctx.ModuleName())
 	if overridden {
 		return ":" + certificate