Please add PSC support for `CustomPythonPackageTrainingJob`

Hi,

Would like to request PSC(Private Service Connect) support added to `CustomPythonPackageTrainingJob`.
Basically i would like to be able to pass PSC related parameter(e.g psc_interface_config or etc) to `CustomPythonPackageTrainingJob` so that it will execute the job using specific PSC interface.

Apparently PSC is able to reduce alot of private IP address usage compared to when using `network` parameter.

Start at the implementation of CustomPythonPackageTrainingJob and trace how its existing network-related parameters are passed into the Vertex AI training request. Compare the supported PSC parameters, such as psc_interface_config, with the job configuration path and add coverage for passing the selected PSC interface; done means the job can execute using that PSC configuration.

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