GGUF support

[BruceMacD]

This change adds support for running GGUF models which are currently in beta with llama.cpp. We will continue to run GGML models and this transition will be seamless to users.

• Adds a llama.cpp mainline submodule which runs GGUF models
• Dynamically select the right runner for the model type
• Moved a some code to different files

./ollama run gguf-codellama hello world

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As mentioned in #423

[BruceMacD]

This is the one difference in the interface between the current mainline llama.cpp and the ggml runner. Im keeping them on the same running logic in hopes that the interface will stay roughly the same. We will see if that changes.

[pdevine]

Looks good... it was slightly confusing trying to figure out the differences between GGUF and GGML. I'm guessing there aren't a lot of differences between the two though.

[pdevine]

Are these (and the constants below here) generic, or specific to GGML?

[BruceMacD]

https://github.com/ggerganov/llama.cpp/blob/d59bd97065cd7ded6c4ecab54b1d5e0b1b11e318/llama.cpp#L1661

Its the number of layers, I dont believe this is GGML specific

[pdevine]

I just went down the rabbit hole on the GGJT controversy. Wow.

[f0rodo]

spill the tea?

[f0rodo]

🚀

[jmorganca]

Overall looks great! Left a small comment on the cmake generate commands