Add built-in column-specific transformers to TableVectorizer

[LilianBoulard]

Fixes part of #554

As discussed in #580, adds the column_specific_transformers parameter to the TableVectorizer.

This allows this kind of functionality:

from skrub import TableVectorizer, MinHashEncoder
from sklearn.compose import make_column_transformer

make_column_transformer([
    (
        MinHashEncoder(),
        ["PRODUCTTYPENAME"],
    ),
    remainder=TableVectorizer(),
])

from the TableVectorizer directly, with this syntax:

TableVectorizer(
    column_specific_transformers=[
        (MinHashEncoder(), ["PRODUCTTYPENAME"])
    ],
)

When the assignements need to be named (e.g. for a grid-search), the user can specify a name (same syntax as the ColumnTransformer):

TableVectorizer(
    column_specific_transformers=[
        ("mh_product_type", MinHashEncoder(), ["PRODUCTTYPENAME"])
    ],
)

[GaelVaroquaux]

Very nice! A few minor comments.

One major one: we should use this in an example. Maybe by modifying an existing one

[GaelVaroquaux]

You have failing tests. Can you address them please

[LilianBoulard]

Thanks for reminding me :)
The PR should be ready to be reviewed/merged now. The implementation is complete and the tests are done.

Concerns were addressed

[jovan-stojanovic]

Thanks @LilianBoulard, nice to see this implemented :)
A few comments for the example

[Vincent-Maladiere]

Hey Lilian, here is my first round of reviews! The example looks neat, let's add the plots from the results of the grid search :)

[LilianBoulard]

The grid-search doesn't work as expected, there is something different between the ColumnTransformer and the TableVectorizer (in the sense, it works with one but not the other), but I don't know what yet. I think you had a concern about set_params @glemaitre?

[LilianBoulard]

So the feature has been ready for a while, but this example is blocking. Since it doesn't work and needs some more work, I've put it into a temporary directory, so it's not accessible on the website, but so we don't lose the code. I'll open an issue in a few minutes to fix that.

[jovan-stojanovic]

I agree that we need to move on, until we find a good solution for the grid search.
Add one more small test before approving this :)

[Vincent-Maladiere]

Thank you @LilianBoulard! After adding the missing test, I'm happy with this PR as-is. Let's investigate the grid-search on a different PR :)

[Vincent-Maladiere]

Let's merge once the CI is green