Reimplement CommunalHub with LazyHorizontalGrid

This change strips out dependency on the CommunalLayoutLib, and
reimplements the UI layer with LazyHorizontalGrid. Now the Compose UI
layer simply renders cards at the given size in the given order. It's up
to upstream layers to decide the sizes and ordering.

Test: verified that CommunalHub renders all three sizes correctly, and
there is no visual delta
Test: veriified that as cards are added / removed, existing cards
maintain state
Bug: 307942173
Fix: 307942173
Flag: ACONFIG com.android.systemui.communal_hub DEVELOPMENT

Change-Id: Ie807b1f1c2e776156ce2c402f372a5bf55064655