feat(runtime): Implement streaming execution output (fixes #1813)

[tinodj]

Closes #1813.

Description

This pull request addresses the lack of real-time feedback during command execution in the DatabricksRuntime.

Problem

Previously, the output of executed commands was buffered and only displayed after the entire process had completed.
For long-running tasks, this left the user without any visibility into the command's progress, making it difficult t
determine if the process was still running or had stalled.

Solution

This PR refactors the execution logic to process output as a stream. This is achieved by:

1. Introducing an onStatusUpdate callback: This function is now passed to the executionContext.execute
   method.
2. Handling Streaming Data: The callback processes output in chunks as they are generated by the remote process
3. Tracking Output Position: A new outputPosition variable tracks the portion of the stream that has already
   been sent to the UI, ensuring that only new output is displayed.

This change provides users with immediate, real-time feedback from their running commands, significantly improving t
user experience.

Testing Notes

This feature has not yet been covered by automated tests. Manual verification is required.

To Test:

1. Run a long-running command (e.g., a Python script with multiple print statements separated by time.sleep
   calls).
2. Confirm that the output appears in the VS Code output panel in real-time as it is generated, rather than all at
   once at the end.

[github-actions]

If integration tests don't run automatically, an authorized user can run them manually by following the instructions below:

Trigger:
go/deco-tests-run/vscode

Inputs:

• PR number: 1814
• Commit SHA: f759bdd4e24467eb1e7a86a4cb9477898be47d3a

Checks will be approved automatically on success.