bootimg and logical_partition are OutputFileProducer

The two module types now implement OutputFileProducer so that we can add
them to the data dependencies of tests.

Bug: 181860941
Test: atest MicrodroidHostTestCase
Change-Id: If263fefb1e5cdb5b57c17eb389c6ecc11d8356f4
diff --git a/filesystem/bootimg.go b/filesystem/bootimg.go
index 764f045..8e2c554 100644
--- a/filesystem/bootimg.go
+++ b/filesystem/bootimg.go
@@ -237,3 +237,13 @@
 func (b *bootimg) OutputPath() android.Path {
 	return b.output
 }
+
+var _ android.OutputFileProducer = (*bootimg)(nil)
+
+// Implements android.OutputFileProducer
+func (b *bootimg) OutputFiles(tag string) (android.Paths, error) {
+	if tag == "" {
+		return []android.Path{b.output}, nil
+	}
+	return nil, fmt.Errorf("unsupported module reference tag %q", tag)
+}