Auxiliary dataframe

[Aggrathon]

As we discussed earlier. It would be nice if all "new columns" (such as embeddings) where part of an "auxiliary" dataframe, since then all new/old plots could automatically use all new/old columns. This PR creates a new dataframe that currently can contain the PCA embedding (computed by xiplot), clusters (computed by xiplot), and selected points. All old plots are updated to handle this new behaviour.

Things to note:

• The auxiliary dataframe is not stored server side (that requires that we update dash_extensions).
• There are new classes for column selection and cluster selection dropdowns (that include easy regex).
• I've tested this in WASM and it seems to be working.
• So much has happened in the repo, so I bumped the version (xiplot should at some point be updated on PyPi as well).

[TanakaAkihiro]

LGTM!

[juntyr]

@Aggrathon I think you missed some validations, though it might also have been me. Apart from the tiny nit I found, it otherwise looks good to me :)