Soong package structure refactoring

Give prebuilt_etc and sh_binary their own packages and split the
gigantic main Android.bp up to small, per-package ones.

Test: m nothing, TreeHugger
Bug: 156980228
Change-Id: I7b00cd344b9f16861f1ff39edf0029f016b853d0
diff --git a/rust/config/Android.bp b/rust/config/Android.bp
new file mode 100644
index 0000000..1a10312
--- /dev/null
+++ b/rust/config/Android.bp
@@ -0,0 +1,19 @@
+bootstrap_go_package {
+    name: "soong-rust-config",
+    pkgPath: "android/soong/rust/config",
+    deps: [
+        "soong-android",
+        "soong-cc-config",
+    ],
+    srcs: [
+        "arm_device.go",
+        "arm64_device.go",
+        "global.go",
+        "toolchain.go",
+        "whitelist.go",
+        "x86_darwin_host.go",
+        "x86_linux_host.go",
+        "x86_device.go",
+        "x86_64_device.go",
+    ],
+}