Rewrite sbox to use a textproto manifest

In preparation for more complicated sandboxing that copies tools
and/or inputs into the sandbox directory, make sbox use a textproto
input that describes the commands to be run and the files to copy
in or out of the sandbox.

Bug: 124313442
Test: m checkbuild
Test: rule_builder_test.go
Test: genrule_test.go
Change-Id: I3b918a6643cea77199fd39577ef71e34cdeacdb1

cmd/sbox/Android.bp

@@ -14,8 +14,20 @@
 
 blueprint_go_binary {
     name: "sbox",
-    deps: ["soong-makedeps"],
+    deps: [
+        "sbox_proto",
+        "soong-makedeps",
+    ],
     srcs: [
         "sbox.go",
     ],
 }
+
+bootstrap_go_package {
+    name: "sbox_proto",
+    pkgPath: "android/soong/cmd/sbox/sbox_proto",
+    deps: ["golang-protobuf-proto"],
+    srcs: [
+        "sbox_proto/sbox.pb.go",
+    ],
+}