[ota] Restructure user consent files (#16549)

* [ota] Restructure user consent files

- Moved user consent related files to respective clusters
- Also, fixed an TODO to get requestor Node ID

* Rename the class names
diff --git a/src/app/BUILD.gn b/src/app/BUILD.gn
index a04cd60..8f7f060 100644
--- a/src/app/BUILD.gn
+++ b/src/app/BUILD.gn
@@ -134,6 +134,7 @@
     "MessageDef/TimedRequestMessage.cpp",
     "MessageDef/WriteRequestMessage.cpp",
     "MessageDef/WriteResponseMessage.cpp",
+    "OTAUserConsentCommon.h",
     "OperationalDeviceProxy.cpp",
     "OperationalDeviceProxy.h",
     "OperationalDeviceProxyPool.h",