Bug: Dill get source string from udf not always work

## Expected Behavior
The dill get source for udf_string won't work if the udf is passed as a param to class. This forces the feature view classes to pass in udf_string instead of infer udf_string from the function.
We need to figure out a way to properlt get the source string for udf.

## Current Behavior

## Steps to reproduce

### Specifications

- Version:
- Platform:
- Subsystem:

## Possible Solution