Fix/suppress aapt/aapt2 google-explicit-constructor warnings

* Add explicit to conversion constructors/operators
* Use NOLINT or NOLINTNEXTLINE to suppress warnings on intended converters

Bug: 28341362
Test: make with WITH_TIDY=1 DEFAULT_GLOBAL_TIDY_CHECKS=-*,google-explicit-constructor
Change-Id: Ie02101ea7c422e8add535c111a30a2f21ead0ace
diff --git a/tools/aapt2/util/Maybe.h b/tools/aapt2/util/Maybe.h
index 031276c..047e1a5 100644
--- a/tools/aapt2/util/Maybe.h
+++ b/tools/aapt2/util/Maybe.h
@@ -44,12 +44,12 @@
   Maybe(const Maybe& rhs);
 
   template <typename U>
-  Maybe(const Maybe<U>& rhs);  // NOLINT(implicit)
+  Maybe(const Maybe<U>& rhs);  // NOLINT(google-explicit-constructor)
 
   Maybe(Maybe&& rhs) noexcept;
 
   template <typename U>
-  Maybe(Maybe<U>&& rhs);  // NOLINT(implicit)
+  Maybe(Maybe<U>&& rhs);  // NOLINT(google-explicit-constructor)
 
   Maybe& operator=(const Maybe& rhs);
 
@@ -64,12 +64,12 @@
   /**
    * Construct a Maybe holding a value.
    */
-  Maybe(const T& value);  // NOLINT(implicit)
+  Maybe(const T& value);  // NOLINT(google-explicit-constructor)
 
   /**
    * Construct a Maybe holding a value.
    */
-  Maybe(T&& value);  // NOLINT(implicit)
+  Maybe(T&& value);  // NOLINT(google-explicit-constructor)
 
   /**
    * True if this holds a value, false if