Fix core tool doc links and user qualification tool default argument values

[cindyyuanjiang]

Fixes #929

Changes

1. Fix stale links in core tool README
2. Update default argument values for user qualification tool

[amahussein]

Thanks @cindyyuanjiang
I am not sure we need to set the default value in every wrapper class. The code internally process the arguments because we might need to reset the default argument depending on the status of the execution.
That's why all the default values for estimation_model was set to None.
P.S: The spark_rapids_user_tools is going to be deprecated.

[amahussein]

Handling the default is done in the ArgProcessor class because there is some logic that is required to calculate the default.
That's why it is set to None in the CLI to be able to distinguish between whether the user left the argument empty or did he actually set the value intentionally.

[cindyyuanjiang]

Thanks @amahussein! I will update this.

[cindyyuanjiang]

Thanks @cindyyuanjiang I am not sure we need to set the default value in every wrapper class. The code internally process the arguments because we might need to reset the default argument depending on the status of the execution. That's why all the default values for estimation_model was set to None. P.S: The spark_rapids_user_tools is going to be deprecated.

Thanks @amahussein! I removed the default values for estimation_model. I kept the default value for filter_apps in spark_rapids to be consistent with the spark_rapids_user_tools, but we can change that if that's not the intended behavior.

The original thought for adding the default values is that when users run spark_rapids qualification -- --help they would see them.

[amahussein]

Thanks @cindyyuanjiang !
The filter_apps better stay None so that we handle the default value in one place .

[amahussein]

Same issue with filter_apps argument.
The filter_apps aregument has some complicated logic to get the default. It depends on the value of other arguments.

[cindyyuanjiang]

Thanks @amahussein! Updated this.

[parthosa]

Thanks @cindyyuanjiang. LGTM

[amahussein]

Thanks @cindyyuanjiang
LGTME