[FSTORE-1411-APPEND] On-Demand Transformation Functions

[manu-sj]

This PR fixes some bugs introduced from logicalclocks/feature-store-api#1371

** Changes Done **

1. Updated check while to set output_column_names for hopsworks_udf so that it does not set the output_column_names if it is empty which can be a possibility when the udf is not attached to a feature view or feature group. Output column names can only be generated when udf is known to be On-Demand (attached to feature group) or Model Dependent (attached to feature view).

2. Changed argument name transformed into transform as per review comments obtained here ([FSTORE-1411] On-Demand Transformations logicalclocks.github.io#397).

3. Updated vector to have variable _on_demand_feature_vector_col_name which store the untransformed and on demand features as a list. This is required to genreate pandas and polars dataframe with correct column names after compute_on_demand_features.

4. Added back changes missed during merge from hopsworks-api to feature-store-api.

JIRA Issue: -

Priority for Review: -

Related PRs:
logicalclocks/feature-store-api#1371
https://github.com/logicalclocks/hopsworks-ee/pull/1862
https://github.com/logicalclocks/loadtest/pull/394

How Has This Been Tested?

• Unit Tests
• Integration Tests
• Manual Tests on VM

Checklist For The Assigned Reviewer:

- [ ] Checked if merge conflicts with master exist
- [ ] Checked if stylechecks for Java and Python pass
- [ ] Checked if all docstrings were added and/or updated appropriately
- [ ] Ran spellcheck on docstring
- [ ] Checked if guides & concepts need to be updated
- [ ] Checked if naming conventions for parameters and variables were followed
- [ ] Checked if private methods are properly declared and used
- [ ] Checked if hard-to-understand areas of code are commented
- [ ] Checked if tests are effective
- [ ] Built and deployed changes on dev VM and tested manually
- [x] (Checked if all type annotations were added and/or updated appropriately)