Fix clang-tidy warnings in camera.

* Add explicit keyword to 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: I71d3008da843ba5f1df1a73a320fb2af6ceffa16
diff --git a/services/camera/libcameraservice/utils/ClientManager.h b/services/camera/libcameraservice/utils/ClientManager.h
index 7ae58d5..830c50b 100644
--- a/services/camera/libcameraservice/utils/ClientManager.h
+++ b/services/camera/libcameraservice/utils/ClientManager.h
@@ -216,7 +216,7 @@
     static constexpr int32_t DEFAULT_MAX_COST = 100;
 
     ClientManager();
-    ClientManager(int32_t totalCost);
+    explicit ClientManager(int32_t totalCost);
 
     /**
      * Add a given ClientDescriptor to the managed list.  ClientDescriptors for clients that