fix: engine init is broken

[louis-jan]

Describe Your Changes

• Fixed an issue where cortex looks for a wrong binary name to download. The engines got different release names. E.g. noavx on llama.cpp but not for others. Platform for both llama.cpp and tensorrt-llm but not onnx.

Fixes Issues

• bug: run llama3:tensorrt-llm leads to "cortex.llamacpp engine not found" #1020
• bug: could not load library ~\cortex/engines/cortex.tensorrt-llm/engine.dll when chatting with model #1021

Self Checklist

• Added relevant comments, esp in complex areas
• Updated docs (for bug fixes / features)
• Created issues for follow-up changes or refactoring needed

[hantran-co]

What are the updates for this @louis-jan i saw it was related to #1020