Create BaseDropOriginalMixin Class

[Chip2916]

As per ticket here

• Added mixin class for transformers that take 'drop_original' argument.
• Added this class to mixin script as per weight class mixin script created during test refactor.
• Added associated tests to the base tests file rather than creating a new script specifically for this (as per weight class mixin also)
• Updated transformers to inherit from new mixin class where required
• Updated test files to inherit from new mixin test class where required and where refactor has taken place

[Chip2916]

Linting errors caused by resolution of merge conflicts, will set up another

[davidhopkinson26]

Looks good, couple of suggestions I would like to see addressed but both minor.

[davidhopkinson26]

I think the comment here could do with extending with ' if self.drop_original is true' as the functionality is not obvious without reading the called function.

[davidhopkinson26]

S - ideally would also have a test that other columns in X are unaffected when dropping columns addressed by the transformer.

[Chip2916]

Thanks for reviewing David, have pushed recommend changes :)

[davidhopkinson26]

Looks good! Thanks 🙏