[ListVnext] Refactor cell layout (height) definition

[sophialee0416]

Platform

• iOS
• macOS

Describe the feature that you would like added

Cell layout (height) definition currently is determined in a List's section. This ensures that any cell within a section will always have uniform height. However, we can also consider moving this as a responsibility for each individual List cell, which will require the client to set the cell height multiple times instead of once. On the other hand, it can allow a List section to have cells of varying height.

We should discuss if having a section of cells with varying height is something should be done, or if we should restrict cells within a section to maintain same height for consistency.

What component or utility would this be added to

ListVnext, ListCellVnext

[sophialee0416]

Part of this will be resolved by Issue #364