[LLDB][Process/Utility] Introduce NativeRegisterContextDBReg class

Since the setup of debug registers for AArch64 and LoongArch is similar,
we extracted the shared logic from Class:
`NativeRegisterContextDBReg_arm64`
into a new Class:
`NativeRegisterContextDBReg`.
This will simplify the subsequent implementation of hardware breakpoints
and watchpoints on LoongArch.

Reviewed By: DavidSpickett

Pull Request: #118043

Author: wangleiat

lldb/source/Plugins/Process/Utility/CMakeLists.txt

@@ -9,6 +9,7 @@ add_lldb_library(lldbPluginProcessUtility
   LinuxSignals.cpp
   MemoryTagManagerAArch64MTE.cpp
   NativeProcessSoftwareSingleStep.cpp
+  NativeRegisterContextDBReg.cpp
   NativeRegisterContextDBReg_arm64.cpp
   NativeRegisterContextDBReg_x86.cpp
   NativeRegisterContextRegisterInfo.cpp