DataView: expose classNames for filter-chip internals and loader rows

Summary

DataView.List renders its rows, cells, and group headers internally, and exposes classNames hooks for them (root, header, headerCell, row, cell, groupHeader, plus per-column cell/header and Filters.classNames.filterChips/addFilter). Two rendered parts still have no hook, so theming them means targeting hashed CSS-module classes ([class*="data-view-module_…"]), which are internal and can change between releases.

What has no hook

1. Filter-chip internals. Filters.classNames.filterChips lands on the chip root only. The inner parts can't be reached: chip-label, operationText, operationValue, selectValue, removeIcon, removeIconContainer, leadingIcon.

2. Loader / skeleton rows. When isLoading renders placeholder rows, there's no hook on the loader container or its rows — DataViewListClassNames covers real rows, not the loading state.

Proposed change

1. Add a classNames object to FilterChip (surfaced through Filters) covering its inner parts.
2. Add a loader (and/or loader-row) key to DataViewListClassNames.

Both follow the pattern the existing hooks already use: read an optional string from props, apply it to the element DataView already renders.

Willing to contribute

Happy to open a PR if the approach looks right.

Start at DataView.List and the FilterChip implementation, then trace how Filters.classNames.filterChips and DataViewListClassNames are applied to rendered elements. Add hooks for the listed filter-chip internals and the loading container or rows, with the existing classNames patterns preserved; done means both areas can be themed without hashed CSS-module selectors.