Autogenerate an android_info module for vendor build.prop

vendor build.prop contains additional board specific properties. An
android_info module will be autogenerated and added as a dep of the
autogenerated vendor-build.prop

The autogenerated module will be created in the root directory, to avoid
complexities such as
1. Creation of additional filegroups if `TARGET_BOARD_INFO_FILES` are
   distributed throughout the tree
2. Scenarios where the filegroups are in a directory that that is
   outside the root soong namespace.

Bug: 375500423
Test: verified that vendor/build.prop is same for kati and soong for
`oriole` (modulo timestamp diffs)

Change-Id: I038a6fc5a5ad87de3cd987be5bdfdbbb1384d0e5
diff --git a/android/variable.go b/android/variable.go
index 2ca7714..142fab9 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -608,6 +608,9 @@
 	VendorLinkerConfigSrcs  []string `json:",omitempty"`
 	ProductLinkerConfigSrcs []string `json:",omitempty"`
 
+	BoardInfoFiles      []string `json:",omitempty"`
+	BootLoaderBoardName string   `json:",omitempty"`
+
 	ProductCopyFiles map[string]string `json:",omitempty"`
 
 	BuildingSystemDlkmImage bool     `json:",omitempty"`