Support passing input variables to the product configuration

Since rblf_env / rblf_cli are not typed properly, accept
input variables via a file so that they can be converted
with the correct types.

Bug: 201700692
Test: go test
Change-Id: I9b56067cfe396d1bcd8d62c353ff222dd61a6c9f

mk2rbc/Android.bp

@@ -38,7 +38,6 @@ bootstrap_go_package {
         "soong_variables.go",
         "types.go",
         "variable.go",
-        "version_defaults.go",
     ],
     deps: ["androidmk-parser"],
 }