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/sh/Android.bp b/sh/Android.bp
new file mode 100644
index 0000000..0b04e7d
--- /dev/null
+++ b/sh/Android.bp
@@ -0,0 +1,16 @@
+bootstrap_go_package {
+    name: "soong-sh",
+    pkgPath: "android/soong/sh",
+    deps: [
+        "blueprint",
+        "soong",
+        "soong-android",
+    ],
+    srcs: [
+        "sh_binary.go",
+    ],
+    testSrcs: [
+        "sh_binary_test.go",
+    ],
+    pluginFor: ["soong_build"],
+}