added support for LlamaLocal's path outside plugin-node/dist

[dr-fusion]

Relates to:

#242

Risks

Low,
User can provide any path for llamalocal and the plugin will direct/load from that directory.

Background

Currently if user tries pnpm build, the node-plugin/dist gets deleted where the downloaded models are stored.
and hence it tries download everytime the build command is executed.

What does this PR do?

This PR will introduce a LLAMALOCAL_PATH environment variable, which can be used to point/download llama models

What kind of change is this?

Improvements (misc. changes to existing features)

Documentation changes needed?

My changes require a change to the project documentation.
It will require to add a new environment variable and it's detail.

Testing

Where should a reviewer start?

Detailed testing steps

1. in the defaultCharacter.ts make sure it has modelProvider: ModelProviderName.LLAMALOCAL
2. now execute pnpm build it will download the NousResearch/Hermes-3-Llama-3.1-8B-GGUF/resolve/main/Hermes-3-Llama-3.1-8B.Q8_0.gguf?download=true models into directory specified in LLAMALOCAL_PATH
3. first time it should display the progress of downloading model.
4. Once the model is downloaded, execute pnpm build again,
5. This time expected behavior and the message should be Model already exists

Discord username

dexbruce