Summary

This PR adds the ability to use a custom rclone executable path instead of relying solely on the system PATH.

Changes

New set_executable_file() Function

• Allows users to specify a custom path to the rclone executable
• Includes an optional validate parameter (default: True) to verify the executable path exists
• Raises FileNotFoundError if the path does not exist and validation is enabled
• Validation can be bypassed with validate=False for advanced use cases

Updated is_installed()

• Previously only checked whether rclone was available in the system PATH
• Now also returns True if a valid custom executable path has been configured via set_executable_file()
• Ensures functions decorated with @__check_installed work correctly when using a custom executable

Tests Added

• test_set_executable_file()
  Verifies that the custom executable path is correctly stored

• test_default_executable_path()
  Confirms the default executable is "rclone"

• test_set_executable_file_validation()
  Tests executable path validation behavior

• test_is_installed_with_custom_executable()
  Ensures is_installed() works correctly with a custom executable path

• test_executable_used_in_command()
  Confirms that the custom executable is actually used when running rclone commands