[WIP] allow python interface to get the default inputs from launch plan

[KyleShao1016]

Tracking issue

Closes flyteorg/flyte#6030

Why are the changes needed?

Initially, the launch plan only retrieved the interface from the workflow. However, this approach could not get the default inputs of the launch plan. Adding a new argument, python_interface, to the launch plan resolves the issue where inputs could not be processed directly from the launch plan.

What changes were proposed in this pull request?

1. adding a new parameter python_interface
2. return this parameter when launch plan is instantiate

How was this patch tested?

Setup process

Screenshots

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

Docs link

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[Mecoli1219]

@KyleShao1016 Three things to update:

1. Sign off your commit
2. It seems like some of your updates break some unit tests. You can either update the broken unit tests or your code to make sure the original unit tests are passed. You can check it with make test command.
3. Create some unit tests related to the bug you fixed. They could be added somewhere like here: https://github.com/flyteorg/flytekit/blob/master/tests/flytekit/unit/core/test_launch_plan.py.