…osoft#24460)

* GroupedList: add new version to address virtualization issues

Introduces a new component, GroupedListV2, that is a drop-in replacement
for GroupedList. GroupedListV2 addresses a bug with the virtualization
implementation in GroupedList. As it is a significant re-write of the
internals we've decided to make it a new component so users can opt in
to the new component/behavior as needed rather than risk significant
breakage with the existing GroupedList implementation.

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Virtualization in GroupedList is powered by List and groups in GroupedList
are nested Lists. When nested with two or more levels of groups issues
can arise with virtualization that result in the vertical size of the
Lists being miscalculated resulting in items not rendering, the scrollbar
repeatedly resizing (causing the list to "jump" about), or both.

List does work asynchronously which contributes to the issue itself and
makes debugging practically impossible as even a simple GroupedList will
contain many Lists all of which are virtualized and rendering async.

To address this issue we are introducing GroupedListV2 which is a drop-in
replacement for GropedList (V1) as it adheres to the same API.

Internally GroupedListV2 flattens virtualization into a single List
eliminating the virtualization bug described above and making the list
easier to reason about and debug.

* List: add conditional rendering option

Adds support to conditionally render cells in List which helps when
rendering flattend GroupedLists as we don't really know if we need to
render certain parts of the list (e.g., footers) until we call the
render function.

Ensure GroupedList <--> GroupedListV2 compatibility.

* DetailsList: allow for custom GroupedList renderer

This change allows users to provide a custom GroupedList renderer like
GroupedListV2.

* Update @fluentui/react API snapshot
Add GroupedListV2 tests
Add DetailsList tests
A dd support for ungrouped lists

* add perf tests for groupedlist/groupedlistv2

* change files

* better types and refactor render functions.

* refactor grouped items

* typescript

* WIP debugging

* fix issues from tests

- Add proper `getKey()` handling.
- Remove selection dependency for "show all" and footer rendering.

* Mark GroupedListV2 as unstable

* groupedlistv2: update naming

- Rename to GroupedListV2_unstable
- Update tests to use this name

* update api snapshot

* update groupedlistv2 import for perf-test

* update snapshots

* pr feedback

* update test snapshot

GroupedListV2 depends on some updates to List that were not present in
the v7 branch. These List changes broke some DetailsList tests so those
have been updated as well.