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/aapt2/SdkConstants.cpp b/tools/aapt2/SdkConstants.cpp
index 91e755d..ccf0383 100644
--- a/tools/aapt2/SdkConstants.cpp
+++ b/tools/aapt2/SdkConstants.cpp
@@ -52,7 +52,7 @@
     return p.first < entryId;
 }
 
-size_t findAttributeSdkLevel(ResourceId id) {
+size_t findAttributeSdkLevel(const ResourceId& id) {
     if (id.packageId() != 0x01 && id.typeId() != 0x01) {
         return 0;
     }