Add EarlyModuleContext for LoadHookContext

Make LoadHookContext embed a new EarlyModuleContext instead of
BaseModuleContext to reduce its API surface in preparation for
moving it to run during parsing instead of mutators.

Test: m checkbuild
Change-Id: I1cd3ff3b636e7e24991a9184d7521903473e505a
diff --git a/java/app.go b/java/app.go
index 94f6bb1..2933ccb 100755
--- a/java/app.go
+++ b/java/app.go
@@ -897,7 +897,7 @@
 	MergePropertiesFromVariant(ctx, &a.properties, archProps, archType.Name)
 }
 
-func MergePropertiesFromVariant(ctx android.BaseModuleContext,
+func MergePropertiesFromVariant(ctx android.EarlyModuleContext,
 	dst interface{}, variantGroup reflect.Value, variant string) {
 	src := variantGroup.FieldByName(proptools.FieldNameForProperty(variant))
 	if !src.IsValid() {