cameraservice: Migrate all internal String8/String16s to std::string

String8 and String16 are deprecated classes. It is recommended to use
std::string or std::u16string wherever possible. String16 is the native
string class for aidl, but Strings marked @utf8InCpp can use std::string
directly.

This patch standardizes libcameraservice's use of strings to
std::string, which is capable of storing utf-8 strings. This makes the
code more readable and potentially reduces the number of string copies
to a minimum.

A new set of string utils is added to frameworks/av/camera to aid this
migration.

Change-Id: I59330ac03c8a52b6c21a2388bba0c143e68af4cf
Bug: 265487852
Test: Presubmit, ran CtsCameraTestCases on Cuttlefish, adb shell dumpsys media camera and observed output
diff --git a/services/camera/libcameraservice/device3/Camera3SharedOutputStream.h b/services/camera/libcameraservice/device3/Camera3SharedOutputStream.h
index 1102ecb..c2ff20e 100644
--- a/services/camera/libcameraservice/device3/Camera3SharedOutputStream.h
+++ b/services/camera/libcameraservice/device3/Camera3SharedOutputStream.h
@@ -37,7 +37,7 @@
             uint32_t width, uint32_t height, int format,
             uint64_t consumerUsage, android_dataspace dataSpace,
             camera_stream_rotation_t rotation, nsecs_t timestampOffset,
-            const String8& physicalCameraId,
+            const std::string& physicalCameraId,
             const std::unordered_set<int32_t> &sensorPixelModesUsed, IPCTransport transport,
             int setId = CAMERA3_STREAM_SET_ID_INVALID,
             bool useHalBufManager = false,