Generate product partition filesystem module in filesystem_creator

Bug: 374388294
Test: CI
Change-Id: I02786d0e9bf1a43a3527b647d5379d35e489076c
diff --git a/android/config.go b/android/config.go
index b70f6ac..686e861 100644
--- a/android/config.go
+++ b/android/config.go
@@ -1558,6 +1558,10 @@
 	return "product"
 }
 
+func (c *deviceConfig) BuildingProductImage() bool {
+	return proptools.Bool(c.config.productVariables.BuildingProductImage)
+}
+
 func (c *deviceConfig) SystemExtPath() string {
 	if c.config.productVariables.SystemExtPath != nil {
 		return *c.config.productVariables.SystemExtPath
diff --git a/android/variable.go b/android/variable.go
index f7392d1..13d5f05 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -337,11 +337,12 @@
 	HWASanIncludePaths []string `json:",omitempty"`
 	HWASanExcludePaths []string `json:",omitempty"`
 
-	VendorPath          *string `json:",omitempty"`
-	BuildingVendorImage *bool   `json:",omitempty"`
-	OdmPath             *string `json:",omitempty"`
-	ProductPath         *string `json:",omitempty"`
-	SystemExtPath       *string `json:",omitempty"`
+	VendorPath           *string `json:",omitempty"`
+	BuildingVendorImage  *bool   `json:",omitempty"`
+	OdmPath              *string `json:",omitempty"`
+	ProductPath          *string `json:",omitempty"`
+	BuildingProductImage *bool   `json:",omitempty"`
+	SystemExtPath        *string `json:",omitempty"`
 
 	ClangTidy  *bool   `json:",omitempty"`
 	TidyChecks *string `json:",omitempty"`