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/FileFinder.h b/tools/aapt/FileFinder.h
index 6974aee..f405381 100644
--- a/tools/aapt/FileFinder.h
+++ b/tools/aapt/FileFinder.h
@@ -72,7 +72,7 @@
      *    time as the value.
      *
      */
-    static void checkAndAddFile(String8 path, const struct stat* stats,
+    static void checkAndAddFile(const String8& path, const struct stat* stats,
                                 Vector<String8>& extensions,
                                 KeyedVector<String8,time_t>& fileStore);