Instrument MCP HTTP Streaming

[amychisholm03]

Description

We have already instrumented MCP's stdio transport; now we need to instrument MCP's streamable HTTP transport.

Acceptance Criteria

The following spans/segments get created according to this spec:

• readResource
• callTool
• getPrompt

Appropriate versioned tests are created.

[Newrelic-Boomi]

https://new-relic.atlassian.net/browse/NR-454005