Auto generate recovery partition

This change conditionally auto generates the recovery partition in
filesystem_generator.

Test: m soong_generated_recovery_filesystem_test
Bug: 381888358
Change-Id: I8938e842d8587ec1c986542385ed50c19dc1c76d
diff --git a/android/variable.go b/android/variable.go
index 25d99da..05ae496 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -351,6 +351,8 @@
 	OemPath               *string `json:",omitempty"`
 	UserdataPath          *string `json:",omitempty"`
 	BuildingUserdataImage *bool   `json:",omitempty"`
+	RecoveryPath          *string `json:",omitempty"`
+	BuildingRecoveryImage *bool   `json:",omitempty"`
 
 	ClangTidy  *bool   `json:",omitempty"`
 	TidyChecks *string `json:",omitempty"`