Camera Extensions: Add Get API feature flag

- add feature flag for CameraExtensionCharacteristics get API

Bug: 280649914
Test: Successful Build
Change-Id: I7efbfddf1fb00c743b216ad14e61e9532916fc26
diff --git a/camera/camera_platform.aconfig b/camera/camera_platform.aconfig
index 2266483..bfbc457 100644
--- a/camera/camera_platform.aconfig
+++ b/camera/camera_platform.aconfig
@@ -86,6 +86,13 @@
 
 flag {
      namespace: "camera_platform"
+     name: "camera_extensions_characteristics_get"
+     description: "Enable get extension specific camera characteristics API"
+     bug: "280649914"
+}
+
+flag {
+     namespace: "camera_platform"
      name: "delay_lazy_hal_instantiation"
      description: "Only trigger lazy HAL instantiation when the HAL is needed for an operation."
      bug: "319735068"