project id initialization from key.json

instead of defining the project id when initializing vertex ai with `const vertex_ai = new VertexAI({project: project, location: location});`, can we make it read from a key.json?

No file or test is named. Start by locating the VertexAI initialization shown in the issue and inspect how key.json is currently handled; done means the project ID can be obtained from key.json instead of requiring the separate project value.

Scritto dal modello di indicizzazione a partire dal testo della issue.