improve OCO_AI_PROVIDER=ollama[/model name] (#327)

* 🐛 (config.ts, engine/ollama.ts, utils/engine.ts): improve Ollama AI configuration and usage
✨ (config.ts): add support for multiple Ollama models and allow users to specify the model in their config
✅ (engine/ollama.ts, utils/engine.ts): refactor code to use the specified Ollama model instead of hardcoding it

* add build results

src/engine/ollama.ts

@@ -3,10 +3,15 @@ import { ChatCompletionRequestMessage } from 'openai';
 import { AiEngine } from './Engine';
 
 export class OllamaAi implements AiEngine {
+  private model = "mistral"; // as default model of Ollama
+
+  setModel(model: string) {
+    this.model = model;
+  }
   async generateCommitMessage(
     messages: Array<ChatCompletionRequestMessage>
   ): Promise<string | undefined> {
-    const model = 'mistral'; // todo: allow other models
+    const model = this.model;
 
     //console.log(messages);
     //process.exit()