MiniGPT-v2 support

[balisujohn]

Posting to gauge/express interested in MiniGPT-v2 support being added.

[Maknee]

Interesting, authors released MiniGPT-v2 as an improvement on minigpt4

I don't have time currently to update the repo to support MiniGPT-v2, but it should be relatively easy to add support for it since the code is using the base model for minigpt4

There's couple things I have in mind to support MiniGPT-v2.

• test out support for llama 2 chat model with minigpt4
• convert the minigpt-v2 model to ggml (the convert.py should automatically do this without any problems)

Most of the work would be with the gui and adding support to the C++ side to handle

• add support to draw on the image
• for each task, add the appropriate api for minigpt to handle (Grounding, Refer, Detection, Identify, VQA)