Auto install pnpm for UI e2e tests in breeze command

[vatsrahul1001]

As highlighted by @potiuk, we should install pnpm if not already installed this PR addresses that.

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[bugraoz93]

Looks good! Thanks Rahul!
I am not against having this in breeze as check and run it but it would be a lot stable and easier to maintain if we install this before even we get here. What this check can do is exit and warn us or anyone checking the logs.

        result = run_command( 
             ["npm", "install", "-g", "pnpm"], 
             no_output_dump_on_exception=True, 
             capture_output=True, 
             text=True, 
             check=False, 
         )

We can install pnpm around here maybe where we already installing additional deps on OS level in docker. Then install_pnpm.sh added to dockerfile which with bash we chan easily do the check if it is installed. If it is in CI image or Prod according to use case, it will be there already in the image and this can fail if we have something wrong with the installation where similar warning as one above method which says install or check script
https://github.com/apache/airflow/tree/main/scripts/docker
Open to discussion, just wanted to share my take on it

[bugraoz93]

If we only want to install for this specific case maybe we can maintain installation here which could be better in the contex of run_command on installing to OS

https://github.com/apache/airflow/tree/main/scripts/in_container/bin