Refactor bp2build tests

Moves to specifying attributes as a map, such at it is possible to add
additional attributes conditionally. This is in particular useful once
supporting the `enabled` property which will add
`target_compatible_with`

Test: go test soong tests
Change-Id: Iade8eed1ce3acb1d1712a9ee3119d9ae59675624
diff --git a/bp2build/apex_key_conversion_test.go b/bp2build/apex_key_conversion_test.go
index 8e1aa09..17f79a6 100644
--- a/bp2build/apex_key_conversion_test.go
+++ b/bp2build/apex_key_conversion_test.go
@@ -43,9 +43,9 @@
         private_key: "com.android.apogee.pem",
 }
 `,
-		expectedBazelTargets: []string{`apex_key(
-    name = "com.android.apogee.key",
-    private_key = "com.android.apogee.pem",
-    public_key = "com.android.apogee.avbpubkey",
-)`}})
+		expectedBazelTargets: []string{makeBazelTarget("apex_key", "com.android.apogee.key", attrNameToString{
+			"private_key": `"com.android.apogee.pem"`,
+			"public_key":  `"com.android.apogee.avbpubkey"`,
+		}),
+		}})
 }