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/CrunchCache.h b/tools/aapt/CrunchCache.h
index be3da5c..4d6a169 100644
--- a/tools/aapt/CrunchCache.h
+++ b/tools/aapt/CrunchCache.h
@@ -81,7 +81,7 @@
      *          // Recrunch sourceFile out to destFile.
      *
      */
-    bool needsUpdating(String8 relativePath) const;
+    bool needsUpdating(const String8& relativePath) const;
 
     // DATA MEMBERS ====================================================