Move create console session button out of action bar

[dhruvisompura]

Description

The create console session split button is currently housed in the console action bar that contains actions which act upon the active console session. The button should be housed elsewhere.

Ideally, this button to be housed in the terminal pane toolbar which would create consistency between the Terminal and Console pane but the VS Code contribution system does not provide a way to create a split button out of the box. The Console pane would need to handle creating the split button in the toolbar as a one off.

The Terminal pane split button utilizes the VS Code context menu which our e2e tests can't interact with. The solution that we go with should support e2e testing.

Some alternatives:

• Move the button to the Console toolbar without the dropdown functionality. The button launches the create new console session quick pick action that the session switcher in the top right uses
• Move the button to the Console toolbar with the dropdown functionality - but use the Positron context menu. Need to verify if this possible
• Move the button to the Console toolbar with the dropdown functionality using the native context menu - but figure out how to pass in a data-testid or some other unique identifier to each menu entry that can be used in our e2e tests.

See addb1e8 for prior art on adding the button to the Console toolbar.

We will need to ensure this the button is only rendered in the toolbar when the console.multipleConsoleSessions feature flag is on.

Testing

This will break e2e tests in test/e2e/tests/console/sessions.test.ts. The tests should be updated so they call the new action.

[petetronic]

Moving this to 2025.06