fs: Add raw_binary rule

Raw binaries are used in bare-metal environments such as early boot of
pVMs (protected virtual machines). Add a new target rule called
'raw_binary' which converts an executable to the raw binary format.

Test: m pvmfw
Change-Id: I701b703a0f12df891b714fe29e320914f167cd04

filesystem/Android.bp

@@ -15,6 +15,7 @@ bootstrap_go_package {
         "bootimg.go",
         "filesystem.go",
         "logical_partition.go",
+        "raw_binary.go",
         "system_image.go",
         "vbmeta.go",
         "testing.go",