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/aapt/WorkQueue.h b/tools/aapt/WorkQueue.h
index d38f05d..ab5f969 100644
--- a/tools/aapt/WorkQueue.h
+++ b/tools/aapt/WorkQueue.h
@@ -47,7 +47,7 @@
     };
 
     /* Creates a work queue with the specified maximum number of work threads. */
-    WorkQueue(size_t maxThreads, bool canCallJava = true);
+    explicit WorkQueue(size_t maxThreads, bool canCallJava = true);
 
     /* Destroys the work queue.
      * Cancels pending work and waits for all remaining threads to complete.