Fix dev container build and GDB setup

[JoelYYoung]

Summary:

• align the Docker image and VS Code task with the SVF Debug build and LLVM 21 CMake package directories
• copy the repository VS Code configurations into the image
• disable GDB debuginfod downloads by default to avoid debugger startup stalls
• add Dev Container ptrace metadata and explicitly install libc6-dbg

Validation:

• Docker build check completed without warnings
• full ARM64 image build completed successfully with Colima
• GDB reached main with SYS_PTRACE enabled and without the vDSO debuginfod stall
• git diff check passed