Add support to generate fsverity metadata

By setting fsverity.inputs, android_filesystem can now generate
.fsv_meta and BuildManifest.apk. It has been done by Makefile because
Makefile is the only one knowing all installed files. But now
android_filesystem is aware of all artifacts, so we can move fsverity
metadata generation into Soong.

Bug: 330282551
Test: m aosp_cf_system_x86_64 and see output
Change-Id: Iae4dd83eaede960c263bfba537211df4ff4b36bd
diff --git a/filesystem/Android.bp b/filesystem/Android.bp
index cead5fc..18dd553 100644
--- a/filesystem/Android.bp
+++ b/filesystem/Android.bp
@@ -18,6 +18,7 @@
         "avb_gen_vbmeta_image.go",
         "bootimg.go",
         "filesystem.go",
+        "fsverity_metadata.go",
         "logical_partition.go",
         "raw_binary.go",
         "system_image.go",