Fix cudastack package names and add missing full variant

Summary

This PR addresses inconsistencies between the cudastack package implementation and its documentation. It ensures that the package can be found using both cudastack and cuda-stack names and implements the missing full variant.

Examples of Issues Fixed

1. Missing full variant and hyphenated name (Documentation matches)

Before:

$ jetson-containers build cuda-stack:full
Error: "couldn't find package: cuda-stack:full"

After:
✅ Finds cudastack:full (alias for cuda-stack:full) and builds with WITH_CUTLASS=1.

2. Base package name discovery

Before:

$ jetson-containers build cudastack
Error: "couldn't find package: cudastack"

After:
✅ Automatically maps to cudastack:standard (the recommended default with TensorRT).

Changes

• Naming Consistency: Added aliases so that both the hyphenated (cuda-stack) and non-hyphenated (cudastack) names now resolve to the correct variants.
• Implemented full Variant: Added the cuda-stack:full variant which includes the CUTLASS build flag as described in the README.
• Improved Base Name Mapping: Mapped the base package names (cuda-stack, cudastack) directly to the standard variant, allowing users to build a default stack with TensorRT without needing explicit tags.
• Aligned minimal Variant: Updated the minimal variant to include NCCL, aligning the code with the existing documentation.
• Bug Fix: Resolved a TypeError in config.py where the global package variable was being improperly handled during list generation.

Motivation

Recently, users following the cudastack/README.md or common naming conventions have encountered KeyError messages because the internal names didn't match the documentation or expected variants. This PR aligns the code with the documentation to provide a smoother experience for users building consolidated CUDA stacks on JetPack 6.

Verification Results

• Verified that find_package() correctly identifies cuda-stack, cudastack, cuda-stack:full, and other variants.
• Verified that the config.py script no longer crashes during package discovery.
• Confirmed that build arguments like WITH_CUTLASS are correctly passed to the Dockerfile based on the chosen variant.