Fold Strategy Updates

[ngupta23]

Describe the changes you've made

Previously, time series experiment only accepted a string as input for fold_strategy. With this change, it can also accept a sktime compatible cv object directly. If an object is passed, then the fold and fh parameters in setup are ignored and are extracted from the cv object directly.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, local variables)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Updated unit tests

Describe if there is any unusual behaviour of your code(Write NA if there isn't)

None

Checklist:

• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• Any dependent changes have been merged and published in downstream modules.