Output apkcerts file for android_app_set.

Soong and Make have no ways to figure out what splits will be outputted
from a given android_app_set, so it's impossible for them to provide
full PACKAGES.$(LOCAL_MODULE).CERTIFICATE entries, which are required to
build a final apkcerts.txt. This change makes extract_apks produce
apkcerts.txt files for each input modules instead. The Make-side
counterpart of this change merges all local apkcerts.txt into a final
one.

Bug: 160119159
Bug: 162464887
Test: main_test.go
Test: m apkcerts-list
Merged-In: I321e80fd636a955213761f56a3ac64bfe7f7f7c0
Change-Id: I321e80fd636a955213761f56a3ac64bfe7f7f7c0

android/module.go

@@ -614,6 +614,33 @@ func (a *ModuleBase) ProductServicesSpecific() bool {
 	return Bool(a.commonProperties.Product_services_specific)
 }
 
+func (m *ModuleBase) PartitionTag(config DeviceConfig) string {
+	partition := "system"
+	if m.SocSpecific() {
+		// A SoC-specific module could be on the vendor partition at
+		// "vendor" or the system partition at "system/vendor".
+		if config.VendorPath() == "vendor" {
+			partition = "vendor"
+		}
+	} else if m.DeviceSpecific() {
+		// A device-specific module could be on the odm partition at
+		// "odm", the vendor partition at "vendor/odm", or the system
+		// partition at "system/vendor/odm".
+		if config.OdmPath() == "odm" {
+			partition = "odm"
+		} else if strings.HasPrefix(config.OdmPath(), "vendor/") {
+			partition = "vendor"
+		}
+	} else if m.ProductSpecific() {
+		// A product-specific module could be on the product partition
+		// at "product" or the system partition at "system/product".
+		if config.ProductPath() == "product" {
+			partition = "product"
+		}
+	}
+	return partition
+}
+
 func (a *ModuleBase) Enabled() bool {
 	if a.commonProperties.Enabled == nil {
 		return !a.Os().DefaultDisabled