sessionId -> sessionResource in task execution and output monitoring

[meganrogge]

part of #274403

[Copilot]

Pull request overview

This pull request migrates task execution and output monitoring components from using string-based sessionId to URI-based sessionResource for tracking chat sessions, as part of the broader effort outlined in issue #274403.

Changes:

• Updated IExecution interface to use sessionResource: URI | undefined instead of sessionId: string | undefined
• Modified OutputMonitor methods to accept and use sessionResource parameter
• Removed unnecessary LocalChatSessionUri import as the code now uses URIs directly

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
types.ts	Changed IExecution interface property from sessionId to sessionResource with proper URI type
outputMonitor.ts	Updated method signatures and implementation to use sessionResource, removed LocalChatSessionUri import, now uses URIs directly with _chatService.getSession()
taskHelpers.ts	Updated execution object creation to assign sessionResource from invocationContext.sessionResource