Separate snapshot definition

Current snapshot definition is located in the CC module, so it is
difficult to capture non-CC module (such as prebuilt_etc) to the
snapshot. Separate general snapshot definition from cc so other modules
can also define its own snapshot.

Bug: 192430376
Test: m nothing passed
Change-Id: Ifb69fb3d2ec555b629aa31ec03e7ce5831fd3063
diff --git a/rust/Android.bp b/rust/Android.bp
index 11069d1..221014e 100644
--- a/rust/Android.bp
+++ b/rust/Android.bp
@@ -11,6 +11,7 @@
         "soong-bloaty",
         "soong-cc",
         "soong-rust-config",
+        "soong-snapshot",
     ],
     srcs: [
         "androidmk.go",