Support deleting console sessions

[samclark2015]

Updates console & runtime infrastructure to add calls/events to enable deletion of sessions. Adds "Trash" button on console session tabs to invoke action.

Screen.Recording.2025-02-21.at.3.28.34.PM.mov

Todo:

• Identify other locations where console sessions are held in state (where do we need to listen for deletion events?)
• Ensure resources are cleaned up effectively (Positron, ExtHost, extensions) so we don't leak memory

Addresses #6311

Release Notes

New Features

• Updates RuntimeSessionService to add API to delete runtime sessions by session ID, and adds event to listen for deleted sessions
• Updates PositronConsoleService to add events when Console sessions are deleted
• Updates PositronConsoleState to listen for deletion events, and modify state to reflect deleted runtimes/sessions
• Updates Console session tabs to add delete button visible on hover

Bug Fixes

• N/A

QA Notes

e2e: @:console

[github-actions]

E2E Tests 🚀
This PR will run tests tagged with: @:critical @:console

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