Add back support for TFJob, PyTorchJob, MPIJob in v1alpha2

[Xinyuan Huang]

The supports for TFJob, PyTorchJob and MPIJob are not complete in the new v1alpha2 codes. We need to add back these support. Required changes for each framework:

• Add manifest modifier
• Add condition checker

[Kirill Prosvirov]

/assign @Akado2009