opentelemetry-instrumentation-vertexai 2.0b0

• Added Vertex AI spans for request parameters (#3192)
• Initial VertexAI instrumentation (#3123)
• Add server attributes to Vertex AI spans (#3208)
• VertexAI emit user, system, and assistant events (#3203)
• Add Vertex gen AI response attributes and gen_ai.choice events (#3227)
• VertexAI stop serializing unset fields into event (#3236)
• Vertex capture tool requests and responses (#3255)