Fix clang-tidy warnings in aapt and aapt2.

* Add explicit keyword to conversion constructors.
* Add NOLINT(implicit) comments for implicit conversion constructors.
Bug: 28341362
* Use const reference type for read-only parameters.
Bug: 30407689
* Use const reference type to avoid unnecessary copy.
Bug: 30413862
Test: build with WITH_TIDY=1

Change-Id: Id6d21961f313a1ad92b15a37fdaa5be9e8ab48e1
diff --git a/tools/aapt2/ConfigDescription.h b/tools/aapt2/ConfigDescription.h
index ef0d147..6858c62 100644
--- a/tools/aapt2/ConfigDescription.h
+++ b/tools/aapt2/ConfigDescription.h
@@ -51,7 +51,7 @@
     static void applyVersionForCompatibility(ConfigDescription* config);
 
     ConfigDescription();
-    ConfigDescription(const android::ResTable_config& o);
+    ConfigDescription(const android::ResTable_config& o);  // NOLINT(implicit)
     ConfigDescription(const ConfigDescription& o);
     ConfigDescription(ConfigDescription&& o);