Allow to set a SetLibrarySearchPath in the golang bindings

[mudler]

This is used to identify the path where all the various implementations are

Describe your changes

This adds SetLibrarySearchPath as model option to search lib path in the specified directory instead of the current work directory.

Issue ticket number and link

#826

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• I have added thorough documentation for my code.
• I have tagged PR with relevant project labels. I acknowledge that a PR without labels may be dismissed.
• If this PR addresses a bug, I have provided both a screenshot/video of the original bug and the working solution.

Demo

Before:

11:59AM DBG Loading model in memory from file: /home/mudler/_git/LocalAI/models/ggml-gpt4all-j                                                                                                                       
Debug: New GPT4ALL                                                                                                                                                                                                          
Debug: Library search path: /tmp/localai/backend_data                                                                                                                                                                       
load_gpt4all_model: error 'Success'                                                                                                                                                                                  
11:59AM DBG [gpt4all] Fails: failed loading mode

After:

gptj_model_load: loading model from '/home/mudler/_git/LocalAI/models/ggml-gpt4all-j' - please wait ...                                                                                                              
gptj_model_load: n_vocab = 50400                                                                                                                                                                                     
gptj_model_load: n_ctx   = 2048                                                                                                                                                                                      
gptj_model_load: n_embd  = 4096
gptj_model_load: n_head  = 16
gptj_model_load: n_layer = 28
gptj_model_load: n_rot   = 64
gptj_model_load: f16     = 2
gptj_model_load: ggml ctx size = 5401.45 MB
gptj_model_load: kv self size  =  896.00 MB
gptj_model_load: ................................... done
gptj_model_load: model size =  3609.38 MB / num tensors = 285
12:01PM DBG [gpt4all] Loads OK
12:01PM DBG Response: {"object":"chat.completion","model":"ggml-gpt4all-j","choices":[{"message":{"role":"assistant","content":"I'm doing well, thank you. How about yourself?"}}],"usage":{"prompt_tokens":0,"comple
tion_tokens":0,"total_tokens":0}}

Steps to Reproduce

This affect only binaries that are not in the same directory within the implementations

Notes

Without this it's impossible to specify a search path to find the various implementations libs.

[niansa]

Looks correct to me, from all I can understand.