Fix system command processing during logging in user tools

[parthosa]

Fixes #632. The cmd argument in run_sys_cmd() in user tools can be of either list or string type. The inner method process_credentials_option() expects cmd to be of list type and processes each item. However, if cmd is of string type, then process_credentials_option() will process each character instead.

Changes:

1. Check the type of the cmd argument and split it into a list if it is of string type.
2. Add type constraints for the cmd argument in run_sys_cmd().

Testing:

The cmd described in the issue has been tested.

Cmd: spark_rapids_user_tools dataproc diagnostic psarthi-dataproc-test -v

Previous output:

2023-10-24 16:19:46,498 DEBUG rapids.tools.cmd_driver: executing CMD:
 <CMD: g c l o u d   c o m p u t e   s s h   p s a r t h i - d a t a p r o c - t e s t - m   - - z o n e   u s - c e n t r a l 1 - a   - - c o m m a n d = " P R E F I X = d i a g _ 2 0 2 3 1 0 2 4 2 3 1 9 0 2 _ E b 9 E E 5 f d   P L A T F O R M _ T Y P E = d a t a p r o c   / t m p / c o l l e c t . s h "   - - f o r m a t   j s o n>[
        <STDOUT>
        | /usr/lib/spark/bin/pyspark
        | Archive '/tmp/diag_20231024231902_Eb9EE5fd_info.tgz' is successfully created!
        | Archive '/tmp/diag_20231024231902_Eb9EE5fd_log.tgz' is successfully created!
        | []]; [
        <STDERR>

Current output:

 <CMD: gcloud compute ssh psarthi-dataproc-test-m --zone us-central1-a --command="PREFIX=diag_20231024231902_Eb9EE5fdPLATFORM_TYPE=dataproc/tmp/collect.sh"--format json>[

[nartal1]

LGTM. Thanks @parthosa !

[cindyyuanjiang]

not sure if this is more concise, nit: cmd_list = cmd if isinstance(cmd, list) else cmd.split(' ')

[parthosa]

Refactored to make it more concise.

[cindyyuanjiang]

Thanks @parthosa!