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
Merged-In: Id6d21961f313a1ad92b15a37fdaa5be9e8ab48e1
diff --git a/tools/aapt2/SdkConstants.h b/tools/aapt2/SdkConstants.h
index 803da03..4a57828 100644
--- a/tools/aapt2/SdkConstants.h
+++ b/tools/aapt2/SdkConstants.h
@@ -44,7 +44,7 @@
     SDK_LOLLIPOP_MR1 = 22,
 };
 
-size_t findAttributeSdkLevel(ResourceId id);
+size_t findAttributeSdkLevel(const ResourceId& id);
 size_t findAttributeSdkLevel(const ResourceName& name);
 
 } // namespace aapt