docs: --output-format flag missing from test command documentation

[A-d-i-t-y]

Describe the bug

Why we need this:
The --output-format flag was added to the test command but is not
documented in documentation/cmd/test.md. Users have no way to
discover this flag from the docs.

How this will help:
Adding this flag to the documentation will help CI/CD users
discover and use the github-actions output format feature.

Problem

The --output-format flag is missing from documentation/cmd/test.md.
The flags table does not include --output-format even though it
is available in the CLI.

Fix

Add --output-format flag to the Options table in test.md with
description and supported values (plain, github-actions).

Attach any resources that can help us understand the issue.

No response

[A-d-i-t-y]

Hi @Harsh4902, I am Aditya, a LFX Mentorship applicant for the IDE Integration and Local Dev Loop Enhancement project. I would like to work on this documentation fix. Could you please assign it to me?