Prework for migrating min_sdk_version from (kind+level) to (level)

This relands aosp/2465355. The original CL was submitted as part of a
stack which broke tm and udc. Those branches contain soong modules with
min_sdk_version of type (kind+level)

Bug: 208456999
Test: go test ./sdk (top of CL stack)
Change-Id: I627f69b1fd71ab386e9026a2fc1566bad786bf1d
diff --git a/sdk/bootclasspath_fragment_sdk_test.go b/sdk/bootclasspath_fragment_sdk_test.go
index efb97be..0d6496d 100644
--- a/sdk/bootclasspath_fragment_sdk_test.go
+++ b/sdk/bootclasspath_fragment_sdk_test.go
@@ -839,6 +839,7 @@
 				compile_dex: true,
 				public: {enabled: true},
 				permitted_packages: ["mysdklibrary"],
+				min_sdk_version: "current",
 			}
 
 			java_sdk_library {