[refactor] replace hardcoded conda env, remove deprecated FindCUDA.cmake, added logic regarding libtorch download

[debashishc]

• Native CUDA Support:

  • Removed the deprecated find_package(CUDA) in favor of native CMake CUDA support using enable_language(CUDA).
  • Set CMake policy CMP0146 to NEW to suppress warnings about FindCUDA.
  • Updated project() declaration to include CUDA as a language.

• Dynamic Conda Environment Detection:

  • Replaced hardcoded Conda environment paths with dynamic detection using the CONDA_PREFIX environment variable.
  • If no Conda environment is detected, a warning is issued, and users are advised to set the environment manually.

• Improved Handling of libtorch:

  • Replaced external wget calls with CMake’s file(DOWNLOAD ...) and execute_process commands for downloading and extracting libtorch.
  • Added logic to check if libtorch is already downloaded to avoid redundant operations or necessity to uncomment.

• Refined Build Process:

  • Ensured that libtorch is properly added to CMAKE_PREFIX_PATH, allowing find_package(Torch REQUIRED) to work as expected.
  • CUDA support is now natively handled without relying on deprecated modules.