Add support for min_sdk_version

Add min_sdk_version properties and use it for aapt2
--min-sdk-version and --target-sdk-version flags.  Add an sdkContext
interface that any function that needs an sdk version can take in
order to get the values for the current module.

Bug: 110848854
Test: m checkbuild
Change-Id: Ic69f1f935d8b865ec77689350407df08bfac5925

java/dex.go

@@ -70,7 +70,12 @@ func (j *Module) dxFlags(ctx android.ModuleContext) []string {
 			"--verbose")
 	}
 
-	flags = append(flags, "--min-api "+j.minSdkVersionNumber(ctx))
+	minSdkVersion, err := sdkVersionToNumberAsString(ctx, j.minSdkVersion())
+	if err != nil {
+		ctx.PropertyErrorf("min_sdk_version", "%s", err)
+	}
+
+	flags = append(flags, "--min-api "+minSdkVersion)
 	return flags
 }